diff --git a/combinatory_logic/README.md b/combinatory_logic/README.md
index 1ff1600..a2a6363 100644
--- a/combinatory_logic/README.md
+++ b/combinatory_logic/README.md
@@ -3,8 +3,12 @@
 * [Flattening Combinators: Surviving Without Parentheses]
   by Chris Okasaki (2003) ([DOI])
 
+* [Combinatorial Analysis and Computers]
+   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
 [DOI]:
     https://doi.org/10.1017/S0956796802004483
+[Combinatorial Analysis and Computers]:
+     https://web.archive.org/web/20170904072400/http://poncelet.math.nthu.edu.tw/disk5/js/computer/hall-knuth.pdf