Added a few Mathematics books and a few HDL (Verilog, VHDL) Books

free-courses-en.md

@@ -1,4 +1,5 @@
 ###Index
+* [Assembly](#assembly)
 * [C++](#c)
 * [Databases](#databases)
 * [Haskell](#haskell)
@@ -10,7 +11,12 @@
 * [Oracle PL/SQL](#oracle-plsql)
 * [Python](#python)
 * [Ruby](#ruby)
-* [Assembly](#assembly)
+
+
+###Assembly
+* [Introduction To Reverse Engineering Software](http://opensecuritytraining.info/IntroductionToReverseEngineering.html)
+* [Introductory Intel x86: Architecture, Assembly, Applications, & Alliteration](http://opensecuritytraining.info/IntroX86.html)
+
 
 ###C++
 * [Google's C++ Course](https://developers.google.com/edu/c++/)
@@ -66,8 +72,3 @@
 
 ###Ruby
 * [RubyMonk - Interactive Ruby tutorials](http://rubymonk.com)
-
-
-###Assembly
-* [Introduction To Reverse Engineering Software](http://opensecuritytraining.info/IntroductionToReverseEngineering.html)
-* [Introductory Intel x86: Architecture, Assembly, Applications, & Alliteration](http://opensecuritytraining.info/IntroX86.html)

free-programming-books.md

@@ -148,6 +148,8 @@
 * [Tizen](#tizen)
 * [TypeScript](#typescript)
 * [Unix](#unix)
+* [Verilog](#verilog)
+* [VHDL](#vhdl)
 * [Vim](#vim)
 * [Visual Prolog](#visual-prolog)
 * [Web Services](#web-services)
@@ -331,13 +333,21 @@
 * [Calculus Made Easy](http://www.gutenberg.org/ebooks/33283) (PDF) - Silvanus P. Thompson
 * [Collaborative Statistics](http://cnx.org/content/col10522/latest/)
 * [Concepts & Applications of Inferential Statistics](http://vassarstats.net/textbook/)
+* [Differential Equations](http://tutorial.math.lamar.edu/pdf/DE/DE_Complete.pdf) - Paul Dawkins 
+* [Elementary Differential Equations](http://ramanujan.math.trinity.edu/wtrench/texts/TRENCH_DIFF_EQNS_I.PDF) - William F. Trench
 * [Essentials of Metaheuristics](http://cs.gmu.edu/~sean/book/metaheuristics/) by Sean Luke
 * [Introduction to Probability](http://www.dartmouth.edu/~chance/teaching_aids/books_articles/probability_book/book.html) - Charles M. Grinstead and J. Laurie Snell
 * [Introduction to Statistical Thought](http://www.math.umass.edu/~lavine/Book/book.html) - Michael Lavine
+* [Linear Algebra](https://www.math.ucdavis.edu/~linear/linear-guest.pdf)
+* [Linear Algebra, Theory And Applications](http://www.math.byu.edu/klkuttle/linearalgebra.pdf) - Kenneth Kuttler
+* [Linear Algebra Done Wrong](http://www.math.brown.edu/~treil/papers/LADW/LADW.pdf) - Sergei Treil
+* [Linear Algebra: An Introduction to Mathematical Discourse](http://en.wikibooks.org/wiki/Linear_Algebra) - Jim Hefferon
 * [Mathematical Logic - an Introduction](http://www.ii.uib.no/~michal/und/i227/book/book.pdf) (PDF)
 * [Mathematics for Computer Science (November 2013 Version)](http://courses.csail.mit.edu/6.042/fall13/mcs.pdf) (PDF) - Eric Lehman
+* [Notes on Differential Equations](http://www.math.cornell.edu/~bterrell/dn.pdf) - Robert E. Terrell
 * [Number Theory](http://web.mit.edu/~holden1/www/math/number-theory.pdf) (PDF)
 * [OpenIntro Statistics](http://www.openintro.org/stat/textbook.php)
+* [Ordinary Differential Equations](http://en.wikibooks.org/wiki/Ordinary_Differential_Equations)
 * [Power Programming with Mathematica](http://mathematica.stackexchange.com/questions/16485/are-you-interested-in-purchasing-david-wagners-power-programming-with-mathemat/22724) - David B. Wagner
 * [Probability and Statistics Cookbook](http://matthias.vallentin.net/probability-and-statistics-cookbook/)
 * [Probability and Statistics EBook](http://wiki.stat.ucla.edu/socr/index.php/Probability_and_statistics_EBook)
@@ -1639,6 +1649,17 @@ See also [LaTeX](#latex)
 * [Unix for Poets](http://www.stanford.edu/class/cs124/kwc-unix-for-poets.pdf) - Kenneth Ward Church (PDF)
 
 
+###Verilog
+* [Introduction to Verilog](http://vol.verilog.com/VOL/main.htm)
+* [Verilog Tutorial](http://www.asic-world.com/verilog/veritut.html)
+
+
+###VHDL
+*[VHDL Tutorial](http://www.seas.upenn.edu/~ese171/vhdl/vhdl_primer.html)
+*[VHDL Tutorial](http://hep.uchicago.edu/~tangjian/SVT_sub/FTK_ATLAS/AUX/vhdl-tutorial.pdf) - Peter J. Ashenden
+*[VHDL Tutorial: Learn By Example](http://esd.cs.ucr.edu/labs/tutorial/)
+
+
 ###Vim
 * [A Byte of Vim](http://www.swaroopch.com/notes/vim/)
 * [A guide to getting started with VIM](http://www.integralist.co.uk/posts/a-guide-to-getting-started-with-vim/)