Added "Open Data Structures: An Introduction"

free-programming-books.md

@@ -188,6 +188,7 @@
 * [Binary Trees](http://cslibrary.stanford.edu/110/BinaryTrees.pdf) (PDF)
 * [Clever Algorithms](http://www.cleveralgorithms.com/nature-inspired/index.html)
 * [Data Structures and Algorithms: Annotated Reference with Examples](https://drive.google.com/file/d/0B48k2jhdQ5P2aVlmMFB1UUJLczA/edit?usp=sharing)
+* [Open Data Structures: An Introduction](http://www.aupress.ca/index.php/books/120226) - Pat Morin
 * [The Algorithm Design Manual](http://www8.cs.umu.se/kurser/TDBAfl/VT06/algorithms/BOOK/BOOK/BOOK.HTM)
 * [LEDA: A Platform for Combinatorial and Geometric Computing](http://www.mpi-inf.mpg.de/~mehlhorn/LEDAbook.html)
 * [Planning Algorithms](http://planning.cs.uiuc.edu/)