diff --git a/datastores/README.md b/datastores/README.md
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 * [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)
 
diff --git a/gamification/README.md b/gamification/README.md
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 ## 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)