Merge pull request #856 from esparta/master

[en] Cleaning up Parallel Programming section

free-programming-books.md

@@ -444,12 +444,12 @@
 * [High Performance Computing Training](https://computing.llnl.gov/?set=training&page=index) (LLNL materials)
 * [High-Performance Scientific Computing](http://bit.ly/hpc12) (class lectures and slides)
 * [How to Write Parallel Programs](http://www.lindaspaces.com/book/)
-* [The OpenCL Programming Book](http://www.fixstars.com/en/opencl/book/OpenCLProgrammingBook/contents/)
 * [Introduction to High-Performance Scientific Computing](http://tacc-web.austin.utexas.edu/veijkhout/public_html/istc/istc.html) - Victor Eijkhout
 * [Introduction to Parallel Computing](https://computing.llnl.gov/tutorials/parallel_comp/) - Blaise Barney
-* [Is Parallel Programming Hard, And, If So, What Can You Do About It?](http://kernel.org/pub/linux/kernel/people/paulmck/perfbook/perfbook.html)
-* [Programming on Parallel Machines; GPU, Multicore, Clusters and More](http://heather.cs.ucdavis.edu/parprocbook) - Norm Matloff
 * [Is Parallel Programming Hard, And, If So, What Can You Do About It?](https://www.kernel.org/pub/linux/kernel/people/paulmck/perfbook/perfbook.html) - Paul E. McKenney
+* [Programming on Parallel Machines; GPU, Multicore, Clusters and More](http://heather.cs.ucdavis.edu/parprocbook) - Norm Matloff
+* [The OpenCL Programming Book](http://www.fixstars.com/en/opencl/book/OpenCLProgrammingBook/contents/)
+
 
 ####Professional Development
 * [Confessions of an IT Manager](http://download.red-gate.com/ebooks/DotNet/Confessions_IT_Manager.zip) *(RedGate, By Phil Factor)*