Merge pull request #1108 from Gluejar/master

the link to the free version is now dead.

free-programming-books.md

@@ -382,7 +382,6 @@
 
 
 #### Misc
-* [97 Things Every Programmer Should Know](http://programmer.97things.oreilly.com/)
 * [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
 * [Asterisk™: The Definitive Guide](http://asteriskdocs.org/en/3rd_Edition/asterisk-book-html-chunk/index.html)
@@ -1730,7 +1729,6 @@ See also [TeX](#tex)
 * [Notes On Programming in TeX](http://pgfplots.sourceforge.net/TeX-programming-notes.pdf) (PDF) by Christian Feursänger
 * [TeX by Topic, A TeXnician's Reference](http://eijkhout.net/texbytopic/texbytopic.html), by Victor Eijkhout
 * [TeX for the Impatient](https://www.gnu.org/software/teximpatient/), by Paul Abrahams, Kathryn Hargreaves, and Karl Berry
-* [The Computer Science of TeX and LaTeX](http://eijkhout.net/texsci/), by Victor Eijkhout
 
 See also [LaTeX](#latex)