Text in periodical Lefford, Nyssim. – «The generative process, music composition and games». – Leonardo. – Vol. 40, no. 2 (2007). – P. 129-135.
Text in periodical Gillette, Frank. – «Random notes on the special case or (loop-de-loop)». – Radical Software. – Vol. 1, no. 1 [(1970)]. – P. 6. Also available on the Internet. {{www.radicalsoftware.org}}