diff --git a/extras/free-books.md b/extras/free-books.md
index 42043f5..bdcaf6e 100644
--- a/extras/free-books.md
+++ b/extras/free-books.md
@@ -48,6 +48,10 @@ Name | Author(s)
 
 ### Math (Discrete Math)
 
+Name | Author(s)
+:-- | :--:
+[Applied Discrete Structures](http://faculty.uml.edu/klevasseur/ads2/) | Alan Doerr, Ken Levasseur
+
 ### Algorithms
 
 ### Programming Paradigms