diff --git a/combinatory_logic/README.md b/combinatory_logic/README.md
index b866a3d..ccd23ac 100644
--- a/combinatory_logic/README.md
+++ b/combinatory_logic/README.md
@@ -1,3 +1,12 @@
-#Combinatory Logic
+# Combinatory Logic
 
-* [Flattening Combinators: Surviving Without Parentheses](http://www.westpoint.edu/eecs/SiteAssets/SitePages/Faculty%20Publication%20Documents/Okasaki/jfp03flat.pdf) by Chris Okasaki
\ No newline at end of file
+* [Flattening Combinators: Surviving Without Parentheses]
+  by Chris Okasaki (2003)
+
+* [Combinatorial Analysis and Computers]
+  by Marshall Hall Jr. and Donald E. Knuth (1965)
+
+[Flattening Combinators: Surviving Without Parentheses]:
+    http://www.westpoint.edu/eecs/SiteAssets/SitePages/Faculty%20Publication%20Documents/Okasaki/jfp03flat.pdf
+[Combinatorial Analysis and Computers]:
+    http://poncelet.math.nthu.edu.tw/disk5/js/computer/hall-knuth.pdf