Added The Haskell Road to Logic, Math and Programming

free-programming-books.md

@@ -577,7 +577,7 @@
 * [Speeding Through Haskell](http://www.sthaskell.com/)
 * [Learn Haskell Fast and Hard](http://yannesposito.com/Scratch/en/blog/Haskell-the-Hard-Way)
 * [Haskell web Programming](http://yannesposito.com/Scratch/fr/blog/Yesod-tutorial-for-newbies/) (Yesod tutorial)
-
+* [The Haskell Road to Logic, Math and Programming](http://fldit-www.cs.uni-dortmund.de/~peter/PS07/HR.pdf) (PDF)
 
 ###HTML / CSS
 * [Dive Into HTML5](http://diveintohtml5.info/) ([PDF](http://mislav.uniqpath.com/2011/10/dive-into-html5/))