Update free-programming-books.md

free-programming-books.md

@@ -398,9 +398,7 @@ Original Source: [Free Programming books](http://stackoverflow.com/revisions/392
 * [Mathematical Logic - an Introduction](http://www.ii.uib.no/~michal/und/i227/book/book.pdf) (PDF)
 * [Mathematics, MTS 101A](http://home.iitk.ac.in/~psraj/mth101/) - P. Shunmugaraj, IIT Kanpur
 * [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)
-* [Numerical Methods](http://www.iitg.ac.in/kartha/CE601-14/CourseSchedule.htm),2014 - Dr. Suresh A. Kartha, IIT, Guwahati
-* [Numerical Methods](ihttp://www.iitg.ac.in/kartha/CE601/LectureSlides.htm),2012 - Dr. Suresh A. Karmtha, IIT, Guwahati
+* [Number Theory](https://github.com/holdenlee/number-theory) - Holden Lee MIT
 * [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
@@ -419,7 +417,7 @@ Original Source: [Free Programming books](http://stackoverflow.com/revisions/392
 
 #### Misc
 * [97 Things Every Programmer Should Know - Extended](https://leanpub.com/97-Things-Every-Programmer-Should-Know-Extended)
-* [A Mathematical Theory of Communication](http://cm.bell-labs.com/cm/ms/what/shannonday/paper.html) by Claude E.Shannon
+* [A Mathematical Theory of Communication](http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6773024) by Claude E.Shannon
 * [Asterisk™: The Definitive Guide](http://asteriskdocs.org/en/3rd_Edition/asterisk-book-html-chunk/index.html)
 * [Barcode Overview](http://www.tec-it.com/download/PDF/Barcode_Reference_EN.pdf)
 * [Come, Let's Play: Scenario-Based Programming Using Live Sequence Charts](http://www.scribd.com/doc/175241338/Come-Let-s-Play)