<ul>
<li><p>Building Problem Solvers by Kenneth D. Forbus and Johan de Kleer: <a href="https://www.qrg.northwestern.edu/BPS/readme.html" class="uri">https://www.qrg.northwestern.edu/BPS/readme.html</a></p></li>
<li><p>Paradigms of Artificial Intelligence Programming by Peter Norvig: <a href="https://github.com/norvig/paip-lisp" class="uri">https://github.com/norvig/paip-lisp</a></p></li>
<li><p>Engineer's Journey, Tuula's blog: <a href="https://engineersjourney.wordpress.com/" class="uri">https://engineersjourney.wordpress.com/</a></p></li>
<li><p>Blog entry about solving n-queens puzzle with general problem solver: <a href="https://engineersjourney.wordpress.com/2018/03/09/n-queens-puzzle-solved-in-hy-and-cps/" class="uri">https://engineersjourney.wordpress.com/2018/03/09/n-queens-puzzle-solved-in-hy-and-cps/</a></p></li>
</ul>