diff --git a/free-programming-books.md b/free-programming-books.md
index 99150b39a7234c560c6aaea61497329ff8e25497..0b263449d5c51db3c75c64f42cfb03dded7b71c6 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -887,6 +887,7 @@ See also [TeX](#tex)
 * [Ruby Learning](http://rubylearning.com/)
 * [Try Ruby](http://tryruby.org/)
 * [Ruby Koans](http://www.rubykoans.com/)
+* [Ruby User's Guide](http://www.rubyist.net/~slagell/ruby/)
 
 
 ###Ruby on Rails