Added "S-99: Ninety-Nine Scala Problems"

free-programming-books.md

@@ -1362,6 +1362,7 @@ See also [TeX](#tex)
 * [Pro Scala: Monadic Design Patterns for the Web](http://github.com/leithaus/XTrace/tree/monadic/src/main/book/content/)
 * [Program Transformation in Scala](http://homepages.cwi.nl/~ai/MScThesis-A-Izmaylova.pdf) - Anastasia Izmaylova
 * [Programming in Scala, First Edition](http://www.artima.com/pins1ed/)
+* [S-99: Ninety-Nine Scala Problems](http://aperiodic.net/phil/scala/s-99/) - Phil! Gold
 * [Scala By Example](http://www.scala-lang.org/docu/files/ScalaByExample.pdf) (PDF)
 * [Scala Cookbook: Bonus Chapters](http://examples.oreilly.com/9781449339616-files/Scala_Cookbook_bonus_chapters.pdf) - Alvin Alexander
 * [Scala & Design Patterns: Exploring Language Expressivity](http://www.scala-lang.org/old/sites/default/files/FrederikThesis.pdf) - Fredrik Skeel Løkke