diff --git a/free-programming-books.md b/free-programming-books.md
index c9ff69eed3688ebe5b6531a90cd6fa641269fc52..cd0c30d08328580a62746500c7281ae336dc1a96 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -415,6 +415,7 @@
 ###IDL
 
 * [Getting Started with IDL](http://www.astro.virginia.edu/class/oconnell/astr511/IDLresources/getting-started-IDL-v7.0.pdf)
+* [Guide to Using IDL for Astronomers](http://www.astro.virginia.edu/class/oconnell/astr511/IDLresources/IDLguide.html)
 
 
 ###Java