Merge pull request EbookFoundation#1765 from 0xCD/patch-1

Added fpc ref guide; removed broken NV gems2 pdf

free-programming-books.md

@@ -230,7 +230,7 @@ Original Source: [List of freely available programming books](http://web.archive
 * [Blender 3D: Noob to Pro](https://en.wikibooks.org/wiki/Blender_3D%3A_Noob_to_Pro)
 * [DirectX manual](http://user.xmission.com/~legalize/book/download/index.html) (draft)
 * [GPU Gems](http://http.developer.nvidia.com/GPUGems/gpugems_part01.html)
-* [GPU Gems 2](http://http.developer.nvidia.com/GPUGems2/gpugems2_part01.html) - [ch 8,14,18,29,30 as pdf](ftp://download.nvidia.com/developer/GPU_Gems_2/)
+* [GPU Gems 2](http://http.developer.nvidia.com/GPUGems2/gpugems2_part01.html)
 * [GPU Gems 3](http://http.developer.nvidia.com/GPUGems3/gpugems3_part01.html)
 * [Graphics Programming Black Book](http://www.gamedev.net/page/resources/_/technical/graphics-programming-and-theory/graphics-programming-black-book-r1698)
 * [Grokking the GIMP](http://gimp-savvy.com/BOOK/index.html)
@@ -955,6 +955,7 @@ Original Source: [List of freely available programming books](http://web.archive
 ### Delphi / Pascal
 
 * [Essential Pascal Version 1 and 2](http://www.marcocantu.com/epascal/)
+* [Free Pascal: Reference guide](http://ftp.icm.edu.pl/packages/fpc/docs-pdf/ref.pdf) (PDF)
 
 
 ### DTrace