diff --git a/free-programming-books.md b/free-programming-books.md
index e466ee0aac1800ed02bc4e552db8246e9af8cd3d..3550fd1d3bdf2e90c6a8ca099c9eab0816aafea6 100644
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@@ -1170,6 +1170,7 @@ See also [TeX](#tex)
 * [Logic, Programming and Prolog (2ed)](http://www.ida.liu.se/~ulfni/lpp/)
 * [Natural Language Processing Techniques in Prolog](http://cs.union.edu/~striegnk/courses/nlp-with-prolog/html/)
 * [Prolog and Natural-Language Analysis](http://www.mtome.com/Publications/PNLA/pnla-digital.html) - Fernando C. N. Pereira, Stuart M. Shieber
+* [Prolog Experiments in Discrete Mathematics, Logic, and Computability](http://web.cecs.pdx.edu/~jhein/books/PrologLabBook09.pdf) - James L. Hein
 * [Prolog for Programmers](https://sites.google.com/site/prologforprogrammers/)
 * [Prolog Techniques](http://bookboon.com/int/student/it/prolog-techniques-applications-of-prolog)
 * [Simply Logical](http://www.cs.bris.ac.uk/~flach/SimplyLogical.html)