fix references in README.md

cryptography/README.md

@@ -1,10 +1,10 @@
 * [A Method for Obtaining Digital Signatures and Public-Key Cryptosystems](http://people.csail.mit.edu/rivest/Rsapaper.pdf)
 * [Twenty Years of Attacks on the RSA Cryptosystem](https://crypto.stanford.edu/~dabo/papers/RSA-survey.pdf)
-* ["Communication Theory of Secrecy Systems"](communication-theory-of-secrecy-systems.pdf)
+* [Communication Theory of Secrecy Systems](communication-theory-of-secrecy-systems.pdf)
 
 ## Related Works
-### ["A Mathematical Theory of Cryptography" (1945) - Shannon](http://www.cs.bell-labs.com/who/dmr/pdfs/shannoncryptshrt.pdf)
+### [A Mathematical Theory of Cryptography (1945)](http://www.cs.bell-labs.com/who/dmr/pdfs/shannoncryptshrt.pdf) - Shannon
 The original classified memo for Bell Labs that was republished in 1949 as ["Communication Theory of Secrecy Systems"](communication-theory-of-secrecy-systems.pdf).
 
-### ["A Mathematical Theory of Communication" (1945) - Shannon](../information_theory/a-mathematical-theory-of-communication-1948.pdf)
+### [A Mathematical Theory of Communication (1948)](../information_theory/a-mathematical-theory-of-communication-1948.pdf) - Shannon
 Shannon said that his wartime insights into communication theory and cryptography developed simultaneously and that "they were so close together you couldn’t separate them". ["Communication Theory of Secrecy Systems"](communication-theory-of-secrecy-systems.pdf) incorporates many concepts and formulations that also appeared in his 1948 paper.