diff --git a/artificial_intelligence/judea_pearl/README.md b/artificial_intelligence/judea_pearl/README.md
index c168de6..533e8fa 100644
--- a/artificial_intelligence/judea_pearl/README.md
+++ b/artificial_intelligence/judea_pearl/README.md
@@ -1,4 +1,4 @@
-[Reverend Bayes on inference engines: A distributed hierarchical approach](http://ftp.cs.ucla.edu/pub/stat_ser/r30.pdf) -
+[Reverend Bayes on inference engines: A distributed hierarchical approach](http://ftp.cs.ucla.edu/pub/stat_ser/r30.pdf) -
> The paper that began the probabilistic revolution in AI
> by showing how several desirable properties of reasoning systems
> can be obtained through sound probabilistic inference.
@@ -6,22 +6,24 @@
> complex probability models, identified conditional independence
> relationships as the key organizing principle for uncertain knowledge,
> and described an efficient, distributed, exact inference algorithm.
-> [ACM Turing Award Short Annotated Bibliography](http://amturing.acm.org/bib/pearl_2658896.cfm)
+> -- [ACM Turing Award Short Annotated Bibliography][1]
[A theory of inferred causation](http://ftp.cs.ucla.edu/pub/stat_ser/r156-reprint.pdf) - with Thomas S. Verma.
> Introduces minimal-model semantics as a basis for causal discovery,
> and shows that causal directionality can be inferred from patterns
> of correlations without resorting to temporal information.
-> [ACM Turing Award Short Annotated Bibliography](http://amturing.acm.org/bib/pearl_2658896.cfm)
+> -- [ACM Turing Award Short Annotated Bibliography][1]
[Causal diagrams for empirical research](http://ftp.cs.ucla.edu/pub/stat_ser/R218-B-L.pdf) - extended version linked.
> Introduces the theory of causal diagrams and its associated do-calculus;
> the first (and still the only) mathematical method to enable a
> systematic removal of confounding bias in observations.
-> [ACM Turing Award Short Annotated Bibliography](http://amturing.acm.org/bib/pearl_2658896.cfm)
+> -- [ACM Turing Award Short Annotated Bibliography][1]
[The algorithmization of counterfactuals](http://ftp.cs.ucla.edu/pub/stat_ser/r360.pdf) -
> Describes a computational model that explains how humans generate,
> evaluate and distinguish counterfactual statements so swiftly and
> consistently.
-> [ACM Turing Award Short Annotated Bibliography](http://amturing.acm.org/bib/pearl_2658896.cfm)
+> -- [ACM Turing Award Short Annotated Bibliography][1]
+
+[1]: http://amturing.acm.org/bib/pearl_2658896.cfm