diff --git a/.github/workflows/lychee.yml b/.github/workflows/lychee.yml
new file mode 100644
index 0000000..ddc0fa6
--- /dev/null
+++ b/.github/workflows/lychee.yml
@@ -0,0 +1,28 @@
+name: lychee
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '0 0 1 * *'
+
+jobs:
+  links:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2.3.4
+   
+    - name: Link Checker
+      uses: lycheeverse/lychee-action@master
+      #env:
+      #  GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
+      with:
+        args: '--verbose --no-progress **/*.md'
+
+    - name: Create Issue From File
+      uses: peter-evans/create-issue-from-file@v2
+      with:
+        title: Link Checker Report
+        content-filepath: ./lychee/out.md
+        labels: report, automated issue
+        
diff --git a/README.md b/README.md
index 52e7345..0de989d 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ If you enjoy the papers, perhaps stop by a local chapter meetup and join in on t
 
 ### Chapters
 
-Here are our official chapters. Let us know if you are interested in [starting one](https://github.com/papers-we-love/papers-we-love/wiki/Creating-a-PWL-chapter) in your city!
+Here are our official chapters. Let us know if you are interested in [starting one](https://github.com/papers-we-love/organizers) in your city!
 
 * [Amsterdam](http://www.meetup.com/papers-we-love-amsterdam/)
 * [Athens](https://www.meetup.com/Papers-We-Love-Athens)
@@ -98,7 +98,7 @@ Please check out our [wiki-page](https://github.com/papers-we-love/papers-we-lov
 Reading a paper is not the same as reading a blogpost or a novel. Here are a few handy resources to help you get started.
 
 * [How to read an academic article](http://organizationsandmarkets.com/2010/08/31/how-to-read-an-academic-article/)
-* [Advice on reading academic papers](https://www.cc.gatech.edu/~akmassey/posts/2012-02-15-advice-on-reading-academic-papers.html)
+* [Advice on reading academic papers](https://userpages.umbc.edu/~akmassey/posts/2012-02-15-advice-on-reading-academic-papers.html)
 * [How to read and understand a scientific paper](http://violentmetaphors.com/2013/08/25/how-to-read-and-understand-a-scientific-paper-2/)
 * [Should I Read Papers?](http://michaelrbernste.in/2014/10/21/should-i-read-papers.html)
 * [The Refreshingly Rewarding Realm of Research Papers](https://www.youtube.com/watch?v=8eRx5Wo3xYA)
diff --git a/android/README.md b/android/README.md
index 5f214c9..73ccde7 100644
--- a/android/README.md
+++ b/android/README.md
@@ -2,7 +2,6 @@
 
 ## Security
 
-* Referenced by [Two Secure Coding Tools for Analyzing Android Apps](http://blog.sei.cmu.edu/post.cfm/secure-coding-tools-analyzing-android-apps-118) :
-    * [Analyzing Inter-Application Communication in Android](https://www.eecs.berkeley.edu/~daw/papers/intents-mobisys11.pdf)
-    * [Effective Inter-Component Communication Mapping in Android with Epicc: An Essential Step Towards Holistic Security Analysis](http://docteau.github.io/pubs/octeau-sec13.pdf)
-    * [FlowDroid: Precise Context, Flow, Field, Object-sensitive and Lifecycle-aware Taint Analysis for Android Apps](http://www.bodden.de/pubs/far+14flowdroid.pdf)
+* [Analyzing Inter-Application Communication in Android](https://www.eecs.berkeley.edu/~daw/papers/intents-mobisys11.pdf)
+* [Effective Inter-Component Communication Mapping in Android with Epicc: An Essential Step Towards Holistic Security Analysis](http://docteau.github.io/pubs/octeau-sec13.pdf)
+* [FlowDroid: Precise Context, Flow, Field, Object-sensitive and Lifecycle-aware Taint Analysis for Android Apps](http://www.bodden.de/pubs/far+14flowdroid.pdf)
diff --git a/combinatory_logic/README.md b/combinatory_logic/README.md
index a2a6363..52aab07 100644
--- a/combinatory_logic/README.md
+++ b/combinatory_logic/README.md
@@ -7,7 +7,7 @@
    by Marshall Hall Jr. and Donald E. Knuth (1965)
 
 [Flattening Combinators: Surviving Without Parentheses]:
-    https://web.archive.org/web/20170828181221/http://www.westpoint.edu:80/eecs/SiteAssets/SitePages/Faculty%20Publication%20Documents/Okasaki/jfp03flat.pdf
+    https://www.cambridge.org/core/services/aop-cambridge-core/content/view/3E99993FE5464986AD94D292FF5EA275/S0956796802004483a.pdf/theoretical-pearls-flattening-combinators-surviving-without-parentheses.pdf
 [DOI]:
     https://doi.org/10.1017/S0956796802004483
 [Combinatorial Analysis and Computers]:
diff --git a/comp_sci_fundamentals_and_history/README.md b/comp_sci_fundamentals_and_history/README.md
index afa5d3d..dcb342e 100644
--- a/comp_sci_fundamentals_and_history/README.md
+++ b/comp_sci_fundamentals_and_history/README.md
@@ -2,7 +2,7 @@
 
 * "Turing, On computable numbers, with an application to the Entscheidungsproblem" by Alan Turing
   * As a PDF: [Turing, On computable numbers, with an application to the Entscheidungsproblem](https://www.cs.virginia.edu/~robins/Turing_Paper_1936.pdf)
-  * As a collection of single images: [Turing, On computable numbers, with an application to the Entscheidungsproblem](http://www.turingarchive.org/browse.php/B/12) by Alan Turing
+  * As a collection of single images: [Turing, On computable numbers, with an application to the Entscheidungsproblem](http://www.cs.virginia.edu/~robins/Turing_Paper_1936.pdf) by Alan Turing
 * [Mealy, A Method for Synthesizing Sequential Circuits](http://www3.alcatel-lucent.com/bstj/vol34-1955/articles/bstj34-5-1045.pdf) by George H. Mealy
 * :scroll: [Back to the Future - The Story of Squeak, A Practical Smalltalk Written in Itself](story-of-squeak-a-practical-smalltalk-written-in-itself.pdf) by Dan Ingalls, Ted Kaehler, John Maloney, Scott Wallace & Alan Kay
 * :scroll: [Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I](recursive-functions-of-symbolic-expressions-and-their-computation-by-machine-parti.pdf) by John McCarthy
diff --git a/computer_graphics/README.md b/computer_graphics/README.md
index 4c256e7..59ddca7 100644
--- a/computer_graphics/README.md
+++ b/computer_graphics/README.md
@@ -9,7 +9,7 @@ This is a really great paper that is both complex and straightforward. This pape
 
 * [Continuous shading of curved surfaces](http://page.mi.fu-berlin.de/block/htw-lehre/wise2015_2016/bel_und_rend/skripte/gouraud1971.pdf) by Henri Gouraud (1971)
 
-* [Illumination for computer generated pictures](http://www.cs.northwestern.edu/~ago820/cs395/Papers/Phong_1975.pdf) by Bui Tuong Phong (1975)
+* [Illumination for computer generated pictures](http://users.cs.northwestern.edu/~ago820/cs395/Papers/Phong_1975.pdf) by Bui Tuong Phong (1975)
 
 * [The Rendering Equation](http://www.cs.rpi.edu/~cutler/classes/advancedgraphics/S08/lectures/kajiya.pdf) by James T. Kajiya (1986)
 
diff --git a/computer_vision/README.md b/computer_vision/README.md
index f03d0d7..6065a5c 100644
--- a/computer_vision/README.md
+++ b/computer_vision/README.md
@@ -1,8 +1,7 @@
 # Computer Vision
 
-* [Coupled 3D Reconstruction of Sparse Facial Hair and Skin](http://www.disneyresearch.com/project/coupled-3d-reconstruction-of-sparse-facial-hair-and-skin/)
-
-* [High-Quality Single-Shot Capture of Facial Geometry](http://www.disneyresearch.com/project/high-quality-single-shot-capture-of-facial-geometry/)
+* [Coupled 3D Reconstruction of Sparse Facial Hair and Skin](http://studios.disneyresearch.com/wp-content/uploads/2019/03/Coupled-3D-Reconstruction-of-Sparse-Facial-Hair-and-Skin.pdf)
+* [High-Quality Single-Shot Capture of Facial Geometry](http://studios.disneyresearch.com/wp-content/uploads/2019/03/High-Quality-Single-Shot-Capture-of-Facial-Geometry/)
 
 * [Panorama Weaving:
 Fast and Flexible Seam Processing](http://www.sci.utah.edu/~bsumma/projects/weaving/)
diff --git a/datastores/README.md b/datastores/README.md
index d83d23c..46f85e4 100644
--- a/datastores/README.md
+++ b/datastores/README.md
@@ -2,7 +2,7 @@
 
 * [Calvin: Fast Distributed Transactions for Partitioned Database Systems](http://cs.yale.edu/homes/thomson/publications/calvin-sigmod12.pdf)
 
-* [f4: Facebook’s Warm BLOB Storage System](http://www-bcf.usc.edu/~wyattllo/papers/f4-osdi14.pdf)
+* [f4: Facebook’s Warm BLOB Storage System](https://www.usenix.org/system/files/conference/osdi14/osdi14-paper-muralidhar.pdf)
 
 * [The Case for Determinism in Database Systems](http://cs-www.cs.yale.edu/homes/dna/papers/determinism-vldb10.pdf)
 
@@ -22,15 +22,15 @@
 
 * [F1: A Distributed SQL Database That Scales](http://static.googleusercontent.com/media/research.google.com/en/us/pubs/archive/41344.pdf)
 
-* [HaLoop: Efficient Iterative Data Processing on Large Clusters](http://www.ics.uci.edu/~yingyib/papers/HaLoop_camera_ready.pdf)
+* [HaLoop: Efficient Iterative Data Processing on Large Clusters](http://homes.cs.washington.edu/~billhowe/pubs/HaLoop.pdf)
 
 * [HyperDex: A Distributed, Searchable Key-Value Store](https://cs.uwaterloo.ca/~bernard/hyperdex.pdf)
 
-* [Introduction to a System for Distributed Databases SDD-1](http://www.few.vu.nl/~kgr700/sdd1.pdf)
+* [Introduction to a System for Distributed Databases SDD-1](http://people.eecs.berkeley.edu/~wong/wong_pubs/wong73.pdf)
 
 * [Making Reliable Distributed Systems in the Presence of Software Errors](http://www.erlang.org/download/armstrong_thesis_2003.pdf)
 
-* [Managing Update Conflicts in Bayou, a Weakly Connected Replicated Storage System](http://zoo.cs.yale.edu/classes/cs422/2013/bib/terry95managing.pdf)
+* [Managing Update Conflicts in Bayou, a Weakly Connected Replicated Storage System](http://www.cs.utexas.edu/~lorenzo/corsi/cs380d/papers/p172-terry.pdf)
 
 * [Map-Reduce-Merge: Simplified Relational Data Processing on Large Clusters](http://www.cs.duke.edu/courses/cps399.28/current/papers/sigmod07-YangDasdanEtAl-map_reduce_merge.pdf)
 
diff --git a/design/README.md b/design/README.md
index 57c76de..e68db20 100644
--- a/design/README.md
+++ b/design/README.md
@@ -1,5 +1,5 @@
 # Design
-* [No Silver Bullet — Essence and Accidents of Software Engineering](http://faculty.salisbury.edu/~xswang/Research/Papers/SERelated/no-silver-bullet.pdf)
+* [No Silver Bullet — Essence and Accidents of Software Engineering](http://www.cs.unc.edu/techreports/86-020.pdf)
 * [Traits: A Mechanism for Fine-Grained Reuse](http://scg.unibe.ch/archive/papers/Duca06bTOPLASTraits.pdf)
 * [THING-MODEL-VIEW-EDITOR an Example from a planningsystem](http://heim.ifi.uio.no/~trygver/1979/mvc-1/1979-05-MVC.pdf)
 
diff --git a/distributed_systems/README.md b/distributed_systems/README.md
index 6ffb0b4..c9437ba 100644
--- a/distributed_systems/README.md
+++ b/distributed_systems/README.md
@@ -35,7 +35,7 @@
 
 * [Paxos Made Live - An Engineering Perspective](http://www.cs.utexas.edu/users/lorenzo/corsi/cs380d/papers/paper2-1.pdf)
 
-* [Practical Byzantine Fault Tolerance and Proactive Recovery](http://www.itu.dk/stud/speciale/bepjea/xwebtex/litt/practical-byzantine-fault-tolerance-and-proactive-recovery.pdf)
+* [Practical Byzantine Fault Tolerance and Proactive Recovery](http://www.microsoft.com/research/wp-content/uploads/2017/01/p398-castro-bft-tocs.pdf)
 
 * [Pregel: A System for Large-Scale Graph Processing](http://kowshik.github.io/JPregel/pregel_paper.pdf)
 
@@ -59,7 +59,7 @@
 
 * [There Is More Consensus in Egalitarian Parliaments](https://www.cs.cmu.edu/~dga/papers/epaxos-sosp2013.pdf)
 
-* [Transactional Client-Server Cache Consistency: Alternatives and Performance](http://www.cs.berkeley.edu/~franklin/Papers/p315-franklin.pdf)
+* [Transactional Client-Server Cache Consistency: Alternatives and Performance](http://drum.lib.umd.edu/bitstream/handle/1903/751/CS-TR-3511.pdf)
 
 * [Unicorn: A System for Searching the Social Graph](http://db.disi.unitn.eu/pages/VLDBProgram/pdf/industry/p871-curtiss.pdf)
 
@@ -176,7 +176,7 @@ Unconditional Sender and Recipient Untraceability](the-dining-cryptographers-pro
 
 * :scroll: [Viewing Control Structures as Patterns of Passing Messages](viewing-control-structures-as-patterns-of-passing-messages.pdf)
 
-* :scroll: [Warp: Multi-Key Transactions for Key-Value Stores](warp-multi-key-transactions-for-key-value-stores.pdf)
+* :scroll: [Warp: Multi-Key Transactions for Key-Value Stores](../datastores/warp-multi-key-transactions-for-key-value-stores.pdf)
 
 * :scroll: [Zab: High-performance broadcast for primary-backup systems](zab-high-performance-broadcast-for-primary-backup-systems.pdf)
 
@@ -191,7 +191,7 @@ Full Cluster Geo-replication](tiered-replication-a-cost-effective-alternative-to
 
 * [Calvin: Fast Distributed Transactions for Partitioned Database Systems](http://cs.yale.edu/homes/thomson/publications/calvin-sigmod12.pdf)
 
-* [f4: Facebook’s Warm BLOB Storage System](http://www-bcf.usc.edu/~wyattllo/papers/f4-osdi14.pdf)
+* [f4: Facebook’s Warm BLOB Storage System](http://www.usenix.org/system/files/conference/osdi14/osdi14-paper-muralidhar.pdf)
 
 * [The Case for Determinism in Database Systems](http://cs-www.cs.yale.edu/homes/dna/papers/determinism-vldb10.pdf)
 
@@ -211,15 +211,15 @@ Full Cluster Geo-replication](tiered-replication-a-cost-effective-alternative-to
 
 * [F1: A Distributed SQL Database That Scales](http://static.googleusercontent.com/media/research.google.com/en/us/pubs/archive/41344.pdf)
 
-* [HaLoop: Efficient Iterative Data Processing on Large Clusters](http://www.ics.uci.edu/~yingyib/papers/HaLoop_camera_ready.pdf)
+* [HaLoop: Efficient Iterative Data Processing on Large Clusters](http://homes.cs.washington.edu/~billhowe/pubs/HaLoop.pdf)
 
 * [HyperDex: A Distributed, Searchable Key-Value Store](https://cs.uwaterloo.ca/~bernard/hyperdex.pdf)
 
-* [Introduction to a System for Distributed Databases SDD-1](http://www.few.vu.nl/~kgr700/sdd1.pdf)
+* [Introduction to a System for Distributed Databases SDD-1](http://people.eecs.berkeley.edu/~wong/wong_pubs/wong73.pdf)
 
 * [Making Reliable Distributed Systems in the Presence of Software Errors](http://www.erlang.org/download/armstrong_thesis_2003.pdf)
 
-* [Managing Update Conflicts in Bayou, a Weakly Connected Replicated Storage System](http://zoo.cs.yale.edu/classes/cs422/2013/bib/terry95managing.pdf)
+* [Managing Update Conflicts in Bayou, a Weakly Connected Replicated Storage System](http://www.cs.utexas.edu/~lorenzo/corsi/cs380d/papers/p172-terry.pdf)
 
 * [Map-Reduce-Merge: Simplified Relational Data Processing on Large Clusters](http://www.cs.duke.edu/courses/cps399.28/current/papers/sigmod07-YangDasdanEtAl-map_reduce_merge.pdf)
 
diff --git a/economics/README.md b/economics/README.md
index 970575b..4ad48db 100644
--- a/economics/README.md
+++ b/economics/README.md
@@ -14,7 +14,7 @@
 
 ## Contract enforcement/principal-agent models
 
-* [Contract Enforceability and Economic Institutions in Early Trade: The Maghribi Traders' Coalition (1993)](https://web.stanford.edu/~avner/Greif_Papers/1993%20Greif%20AER%201993.pdf) by Avner Grief
+* [Contract Enforceability and Economic Institutions in Early Trade: The Maghribi Traders' Coalition (1993)](https://web.stanford.edu/~avner/Greif_Papers/1993%20Greif%20AER%201993.pdf) by Avner Greif
 
 ## Game theory
 
diff --git a/gamification/README.md b/gamification/README.md
index daf2c7b..76645e0 100644
--- a/gamification/README.md
+++ b/gamification/README.md
@@ -2,7 +2,7 @@
 
 ## External Papers
 
-* [Defining Gamification - A Service Marketing Perspective](http://www.rolandhubscher.org/courses/hf765/readings/p17-huotari.pdf)
+* [Defining Gamification - A Service Marketing Perspective](https://www.researchgate.net/publication/259841647_Defining_Gamification_-_A_Service_Marketing_Perspective)
 
 * [Design Requirements for Technologies that Encourage Physical Activity](https://www.cs.helsinki.fi/u/thusu/opinnot/uschool/T-121.5500/p457-consolvo.pdf)
 
diff --git a/garbage_collection/README.md b/garbage_collection/README.md
index 11d6ca4..5183aab 100644
--- a/garbage_collection/README.md
+++ b/garbage_collection/README.md
@@ -5,8 +5,9 @@
 * [Incremental Collection of Mature Objects](http://pdf.aminer.org/000/465/194/incremental_collection_of_mature_objects.pdf)
 * [:scroll:](incremental_mature_garbage_collection_using_the_train_algorithm.pdf) [Incremental Mature Garbage Collection Using the Train Algorithm](https://www.sics.se/~seif/DatalogiII/Book/train.ps)
 * [Incremental Garbage Collection: The Train Algorithm](http://www.ssw.uni-linz.ac.at/General/Staff/TW/Wuerthinger05Train.pdf)
-* [:scroll:](the_lisp_ii_garbage_collector.pdf) [The Lisp II Garbage Collector](ftp://publications.ai.mit.edu/ai-publications/pdf/AIM-019.pdf)
-* [The Treadmill: Real-Time Garbage Collection Without Motion Sickness](http://home.pipeline.com/~hbaker1/NoMotionGC.html)
+* [On-the-Fly Garbage Collection: An Exercise in Cooperation](https://lamport.azurewebsites.net/pubs/garbage.pdf)
+* [:scroll:](the_lisp_ii_garbage_collector.pdf) [The Lisp II Garbage Collector](http://www.softwarepreservation.com/projects/LISP/lisp2/TM-3417_500_00_LISP2_GC_Spec.pdf)
+* [The Treadmill: Real-Time Garbage Collection Without Motion Sickness](http://plover.com/~mjd/misc/hbaker-archive/NoMotionGC.html)
 * [Parallel Generational-Copying Garbage Collection with a Block-Structured
-  Heap](http://community.haskell.org/~simonmar/papers/parallel-gc.pdf)
+  Heap](http://simonmar.github.io/bib/papers/parallel-gc.pdf)
 
diff --git a/gossip/README.md b/gossip/README.md
index 5578b3a..e5d127a 100644
--- a/gossip/README.md
+++ b/gossip/README.md
@@ -7,10 +7,10 @@ If you only read one of these papers, start with the classic Demers, et al paper
 Briefly, a peer sampling service is a system that maintains a restricted set (partial view) of the all machines participating in a gossip system.
 * [The Peer Sampling Service: Experimental Evaluation of Unstructured Gossip-Based Implementations](http://infoscience.epfl.ch/record/83409/files/neg--1184036295all.pdf)
 * [HyParView: a membership protocol for reliable gossip-based broadcast](http://asc.di.fct.unl.pt/~jleitao/pdf/dsn07-leitao.pdf)
-* [SWIM: Scalable Weakly-consistent Infection-style Process Group Membership Protocol](http://www.cs.cornell.edu/info/projects/spinglass/public_pdfs/swim.pdf)
+* [SWIM: Scalable Weakly-consistent Infection-style Process Group Membership Protocol](http://research.cs.cornell.edu/projects/Quicksilver/public_pdfs/SWIM.pdf)
 
 # Epidemic broadcast 
-* [Large-Scale Newscast Computing on the Internet ](http://www.soc.napier.ac.uk/~benp/dream/dreampaper17.pdf)
+* [Large-Scale Newscast Computing on the Internet ](http://www.researchgate.net/profile/Maarten-Van-Steen/publication/2479853_Large-Scale_Newscast_Computing_on_the_Internet/links/579132c708ae0831552f97f4/Large-Scale-Newscast-Computing-on-the-Internet.pdf)
 * [Bimodal Multicast](http://www.csl.mtu.edu/cs6461/www/Reading/Birman99.pdf)
 * [Efficient Reconciliation and Flow Control for Anti-Entropy Protocols](http://www.cs.cornell.edu/home/rvr/papers/flowgossip.pdf)
 * [Epidemic Broadcast Trees](http://www.gsd.inesc-id.pt/~ler/reports/srds07.pdf)
diff --git a/languages-theory/README.md b/languages-theory/README.md
index b0488e4..680fe02 100644
--- a/languages-theory/README.md
+++ b/languages-theory/README.md
@@ -1,6 +1,6 @@
 # Programming Language Theory
 
-* [Can Programming Be Liberated from the von Neumann Style? A Functional Style and Its Algebra of Programs](http://www.thocp.net/biographies/papers/backus_turingaward_lecture.pdf)
+* [Can Programming Be Liberated from the von Neumann Style? A Functional Style and Its Algebra of Programs](https://dl.acm.org/doi/pdf/10.1145/359576.359579)
 
 * [:scroll:](https://github.com/papers-we-love/papers-we-love/blob/master/languages-theory/programming-with-algebraic-effects-and-handlers.pdf) [Programming and Reasoning with Algebraic Effects and Dependent Types](http://eb.host.cs.st-andrews.ac.uk/drafts/effects.pdf)
 
diff --git a/logic_and_programming/README.md b/logic_and_programming/README.md
index c0978f3..17537ea 100644
--- a/logic_and_programming/README.md
+++ b/logic_and_programming/README.md
@@ -3,4 +3,4 @@
 * :scroll: [Representing Game Dialogue as Expresions in First-Order Logic](representing-game-dialogue-as-expressions-in-first-order-logic.pdf)
 * :scroll: [The Event Calculus as a Linear Logic Program](event-calculus.txt)
 * [Purely Functional Lazy Non-deterministic Programming](http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.148.524)
-* [:scroll:](on-the-meanings-of-the-logical-constants.pdf) [On the Meanings of the Logical Constants and the Justifications of the Logical Laws](http://www.pps.univ-paris-diderot.fr/~saurin/Enseignement/LMFI/articles/Martin-Lof83.pdf)
+* [:scroll:](on-the-meanings-of-the-logical-constants.pdf) [On the Meanings of the Logical Constants and the Justifications of the Logical Laws](http://uberty.org/wp-content/uploads/2017/06/Martin-Lof83.pdf)
diff --git a/machine_learning/README.md b/machine_learning/README.md
index 10f6140..550667c 100644
--- a/machine_learning/README.md
+++ b/machine_learning/README.md
@@ -34,7 +34,7 @@
 
   This paper introduces an explanation technique for any classifier in a interpretable manner. 
 
-* [Multiple Narrative Disentanglement: Unraveling *Infinite Jest*](http://dreammachin.es/p1-wallace.pdf)
+* [Multiple Narrative Disentanglement: Unraveling *Infinite Jest*](http://aclanthology.org/N12-1001.pdf)
 
   Uses an unsupervised approach to natural language processing that classifies narrators in David Foster Wallace's 1,000-page novel.
 
diff --git a/privacy/README.md b/privacy/README.md
index ec60663..15bc04b 100644
--- a/privacy/README.md
+++ b/privacy/README.md
@@ -1,10 +1,10 @@
 ## Privacy
 
-* [k-ANONYMITY: A model for Protecting Privacy (1998)](https://dataprivacylab.org/dataprivacy/projects/kanonymity/kanonymity.pdf)
+* [k-ANONYMITY: A model for Protecting Privacy (1998)](https://epic.org/wp-content/uploads/privacy/reidentification/Sweeney_Article.pdf)
 * [Differential Privacy(2006)](https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/dwork.pdf)
 * [Robust De-anonymization of Large Sparse Datasets(2008)](https://www.cs.utexas.edu/~shmat/shmat_oak08netflix.pdf)
 * [Broken Promises of Privacy: Responding to the Surprising Failure of Anonymization(2010)](https://www.uclalawreview.org/broken-promises-of-privacy-responding-to-the-surprising-failure-of-anonymization-2/)
-* [Timing Attacks on Web Privacy(2000)](https://sip.cs.princeton.edu/pub/webtiming.pdf)
+* [Timing Attacks on Web Privacy(2000)](https://www.cs.jhu.edu/~fabian/courses/CS600.424/course_papers/webtiming.pdf)
 * [Protecting Browser State from Web Privacy Attacks(2006)](https://crypto.stanford.edu/sameorigin/sameorigin.pdf)
 * [KHyperLogLog: Estimating Reidentifiability and
 Joinability of Large Data at Scale(2019)](https://storage.googleapis.com/pub-tools-public-publication-data/pdf/40bc2804cbd3e41ed28dc8991316361eca48630c.pdf)
diff --git a/quantum_computing/README.md b/quantum_computing/README.md
index d7391a0..8bbb66a 100644
--- a/quantum_computing/README.md
+++ b/quantum_computing/README.md
@@ -2,8 +2,8 @@
 
 ## Included Papers
 
-* [:scroll:](advance_in_quantum_machine_learning.pdf) [Advances in quantum machine learning (2015)](https://arxiv.org/abs/1512.02900) (Jeremy Adcock, Euan Allen, Matthew Day, Stefan Frick, Janna Hinchliff, Mack Johnson, Sam Morley-Short, Sam Pallister, Alasdair Price, Stasja Stanisic)
+* :scroll: [Advances in quantum machine learning (2015)](advance_in_quantum_machine_learning.pdf) (Jeremy Adcock, Euan Allen, Matthew Day, Stefan Frick, Janna Hinchliff, Mack Johnson, Sam Morley-Short, Sam Pallister, Alasdair Price, Stasja Stanisic)
 
-* [:scroll:](shors_algorithm.pdf) [Shors algorithm for polynomial time prime factorization (1995)](https://arxiv.org/pdf/quant-ph/9508027.pdf) (Peter W Shor)
+* :scroll: [Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer](shors_algorithm.pdf) (Peter W Shor)
 
-* [:scroll:](grovers_algorithm.pdf) [A fast quantum mechanical algorithm for database search](https://arxiv.org/pdf/quant-ph/9605043.pdf) (Lov K. Grover)
+* :scroll: [A fast quantum mechanical algorithm for database search](grovers_algorithm.pdf) (Lov K. Grover)
diff --git a/scripts/download.sh b/scripts/download.sh
index d5139d4..4d6d42c 100755
--- a/scripts/download.sh
+++ b/scripts/download.sh
@@ -11,7 +11,7 @@ download_for_directory() {
 
     for f in *; do
         if [[ -d ${f} ]]; then
-            download_for_directory ${f} &
+            download_for_directory "./${f}" &
         fi
     done
 
diff --git a/security/README.md b/security/README.md
index cf9fec4..326df66 100644
--- a/security/README.md
+++ b/security/README.md
@@ -5,7 +5,7 @@
 * [Looking inside the (Drop) Box (2013)](https://www.usenix.org/system/files/conference/woot13/woot13-kholia.pdf)
 * [Making Programs Forget: Enforcing Lifetime For Sensitive Data (2011)](https://www.usenix.org/events/hotos11/tech/final_files/Kannan.pdf)
 * [Breach: Reviving The Crime Attack (2013)](http://breachattack.com/resources/BREACH%20-%20SSL,%20gone%20in%2030%20seconds.pdf)
-* [Why Silent Updates Boost Security (2009)](http://www.techzoom.net/Papers/Browser_Silent_Updates_%282009%29.pdf)
+* [Why Silent Updates Boost Security (2009)](http://tik-old.ee.ethz.ch/file/ef72343372ca8659a9ae8a98873167c0/TIKReport302.pdf)
 * [A survey of coordinated attacks and collaborative intrusion detection (2010)](https://www.tk.informatik.tu-darmstadt.de/fileadmin/user_upload/Group_TK/zhou2010survey.pdf)
 
 * :scroll: [Macaroons: Cookies with Contextual Caveats for Decentralized Authorization in the Cloud (2014)](macaroons-cookies-with-contextual-caveats.pdf)
diff --git a/software_engineering_orgs/README.md b/software_engineering_orgs/README.md
index a78f3c0..48f8802 100644
--- a/software_engineering_orgs/README.md
+++ b/software_engineering_orgs/README.md
@@ -15,7 +15,7 @@ The [practice of software engineering](https://en.wikipedia.org/wiki/Software_en
 
 ## Organizational Simulation
 
-* [:scroll:](common-ground-and-coordination-in-joint-activity.pdf) [Common Ground and Coordination in Joint Activity](http://jeffreymbradshaw.net/publications/Common_Ground_Single.pdf) by Klein, Feltovich, and Woods
+* [:scroll:](common-ground-and-coordination-in-joint-activity.pdf) [Common Ground and Coordination in Joint Activity](http://www.researchgate.net/profile/David-Woods-19/publication/227992178_Common_Ground_and_Coordination_in_Joint_Activity/links/5ba284c892851ca9ed15cdc0/Common-Ground-and-Coordination-in-Joint-Activity.pdf) by Klein, Feltovich, and Woods
 
   > The paper is the result of what happens when people with backgrounds in mathematics, psychology, and artificial intelligence (Feltovich and Bradshaw) get together to ask questions about how teams operate alongside the originators of modern decision-making and cognitive systems engineering research (Klein and Woods). The concepts outlined in the paper have provided frames and directions in designing tools and environments where successful work requires multiple actors (whether they are people or software agents!) to succeed. This seminal paper takes a deep dive into not just people and teamwork, but what comprises the sometimes invisible activity of coordination, collaboration, cooperation, and the contracts and expectations entities have with each other along the way. The paper has had far-reaching influence in multiple domains: military intelligence, space transportation and aviation, and more recently: software engineering and operations on the web. Let me walk you through where this paper came from, what makes this paper critical to the future of software, and a hint about what I'm sure it means about the future. - @allspaw 
 
diff --git a/unikernels/README.md b/unikernels/README.md
index 43311f9..1517fc5 100644
--- a/unikernels/README.md
+++ b/unikernels/README.md
@@ -7,18 +7,18 @@
 * [A persistent system in real use-experiences of the first 13 years](https://os.itec.kit.edu/downloads/publ_1993_liedtke_persistent-system-in-real-use.pdf)
 * [SPIN: An extensible microkernel for application-specific operating system services](https://apps.dtic.mil/dtic/tr/fulltext/u2/a293537.pdf)
 * [Extensibility safety and performance in the SPIN operating system](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.117.6702&rep=rep1&type=pdf)
-* [Policy/mechanism separation in Hydra](https://www.systems.ethz.ch/sites/default/files/file/aos2012/Reading/week9/Policy%20mechanism%20separation%20in%20Hydra.pdf)
+* [Policy/mechanism separation in Hydra](http://www.cse.psu.edu/~trj1/cse543-f12/docs/p132-levin-hydra.pdf)
 * [Improving IPC by kernel design](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.55.9939&rep=rep1&type=pdf)
 
 ## Second-wave: cloud optimization (exokernels, multikernels)
 
 * [Exokernel: An operating system architecture for application-level resource management](http://pages.cs.wisc.edu/~remzi/Classes/736/Spring2014/Papers/exo-sosp95.pdf)
 * [Exterminate all operating system abstractions](http://studies.ac.upc.es/doctorat/ENGRAP/hotos-jeremiad.pdf)
-* [The Clive Operating System](http://lsub.org/export/clivesys.pdf)
+* [The Clive Operating System](http://github.com/fjballest/docs/blob/master/clivesys.pdf)
 * [The Multikernel: A new OS architecture for scalable multicore systems](http://www.cse.iitd.ac.in/~sbansal/csl862-os/readings/barrelfish.pdf)
 * [IX: A Protected Dataplane Operating System for High Throughput and Low Latency](https://www.usenix.org/system/files/conference/osdi14/osdi14-paper-belay.pdf)
 * [The IX Operating System: Combining Low Latency, High Throughput, and Efficiency in a Protected Dataplane](https://infoscience.epfl.ch/record/223617/files/tocs16-ix.pdf)
-* [Contiki - a lightweight and flexible operating system for tiny networked sensors](http://perso.citi.insa-lyon.fr/trisset/cours/rts12/articles/DGV04-contiki.pdf)
+* [Contiki - a lightweight and flexible operating system for tiny networked sensors](http://dunkels.com/adam/dunkels04contiki.pdf)
 * [Arrakis: The Operating System Is the Control Plane](https://dl.acm.org/citation.cfm?id=2812806)
 * [Embracing diversity in the Barrelfish manycore operating system](http://www.barrelfish.org/publications/barrelfish_mmcs08.pdf)
 * [Decoupling Cores, Kernels, and Operating Systems](https://www.usenix.org/system/files/conference/osdi14/osdi14-paper-zellweger.pdf)
@@ -33,12 +33,12 @@
 * [Breaking up is hard to do: security and functionality in a commodity hypervisor](https://open.library.ubc.ca/media/download/pdf/24/1.0052016/1)
 * [A case for high performance computing with virtual machines](http://mvapich.cse.ohio-state.edu/static/media/publications/abstract/huangwei-ics06.pdf)
 * [Comparing the robustness of POSIX operating systems](https://users.ece.cmu.edu/~koopman/ballista/ftcs99/ftcs99.pdf)
-* [Exploring the Design Space of Combining Linux with Lightweight Kernels for Extreme Scale Computing](http://www.sys.r-ccs.riken.jp/members_files/bgerofi/papers/ross15-linux+lwk.pdf)
+* [Exploring the Design Space of Combining Linux with Lightweight Kernels for Extreme Scale Computing](http://www.mcs.anl.gov/events/workshops/ross/2015/slides/ross2015-gerofi.pdf)
 * [Using kernel hypervisors to secure applications](https://ieeexplore.ieee.org/abstract/document/646188)
 
 ### Specific libOS implementations
 
-* [IncludeOS: A minimal, resource efficient unikernel for cloud services](http://folk.uio.no/paalee/publications/2015-cloudcom.pdf)
+* [IncludeOS: A minimal, resource efficient unikernel for cloud services](http://oda.oslomet.no/oda-xmlui/bitstream/handle/10642/3189/1321835.pdf)
 * [OSv—optimizing the operating system for virtual machines](https://www.usenix.org/system/files/conference/atc14/atc14-paper-kivity.pdf)
 * [ClickOS and the art of network function virtualization](https://www.usenix.org/system/files/conference/nsdi14/nsdi14-paper-martins.pdf)
 * [Enabling fast, dynamic network processing with clickos](http://conferences.sigcomm.org/sigcomm/2013/papers/hotsdn/p67.pdf)
@@ -53,7 +53,7 @@
 
 * [The impact of operating system structure on memory system performance](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.52.4651&rep=rep1&type=pdf)
 * [Hypervisors vs. Lightweight Virtualization: A Performance Comparison](https://www.researchgate.net/profile/Roberto_Morabito/publication/273756984_Hypervisors_vs_Lightweight_Virtualization_A_Performance_Comparison/links/550a83660cf26198a63afb10.pdf)
-* [A performance evaluation of rump kernels as a multi-server os building block on sel4](http://echronos.systems/publications/csiro_full_text/Elphinstone_ZMH_17.pdf)
+* [A performance evaluation of rump kernels as a multi-server os building block on sel4](http://trustworthy.systems/publications/csiro_full_text/Elphinstone_ZMH_17.pdf)
 * [An updated performance comparison of virtual machines and linux containers](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.471.9242&rep=rep1&type=pdf)
 * [My VM is Lighter (and Safer) than your Container](https://dl.acm.org/citation.cfm?id=3132763)
 * [Security of OS-level virtualization technologies: Technical report](https://arxiv.org/pdf/1407.4245v1.pdf)
@@ -72,7 +72,6 @@
 * [uniprof: A Unikernel Stack Profiler](https://flosch.eu/papers/2017-sigcomm-uniprof.pdf)
 * [On the Fly TCP Acceleration with Miniproxy](https://arxiv.org/pdf/1605.06285.pdf)
 * [Unikernel monitors: extending minimalism outside of the box](https://www.usenix.org/system/files/conference/hotcloud16/hotcloud16_williams.pdf)
-* [Unikernels As Processes](https://sjmulder.nl/dl/pdf/2018%20-%20Williams%20et%20al%20-%20Unikernels%20as%20Processes.pdf)
+* [Unikernels As Processes](https://dl.acm.org/doi/pdf/10.1145/3267809.3267845)
 * [On the Fly Orchestration of Unikernels: Tuning and Performance Evaluation of Virtual Infrastructure Managers](https://arxiv.org/pdf/1809.07701.pdf)
 * [Live updating in Unikernels](https://www.duo.uio.no/bitstream/handle/10852/59240/45/live-updating-unikernels.pdf)
-* [Android Unikernel: Gearing mobile code offloading towards edge computing](http://grid.hust.edu.cn/wusong/file/FGCS18.pdf)
\ No newline at end of file