the link to the free version is now dead.

free-programming-books.md

@@ -1730,7 +1730,6 @@ 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)