Update free-programming-books.md

free-programming-books.md

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 * [Animation/Games in Java](http://www.heatonresearch.com/articles/series/3)
 * [Apache Jakarta Commons: Reusable Java Components](http://ptgmedia.pearsoncmg.com/images/0131478303/downloads/Iverson_book.pdf) - Will Iverson
 * [Artificial Intelligence - Foundation of Computational Agents](http://artint.info/html/ArtInt.html)
+* [Cadmus: A Primer in Java](http://java.divshot.io) - Hashan Punchihewa, Joseph Bills et al.
 * [Category wise tutorials - J2EE](http://www.mkyong.com/)
 * [Core Servlets and JavaServer Pages](http://pdf.coreservlets.com/) - Marty Hall and Larry Brown
 * [Data Structures and Algorithms with Object-Oriented Design Patterns in Java](http://www.brpreiss.com/books/opus5/html/page9.html)