an American computer scientist and early computer chess programmer when he was undergraduate student at University of Waterloo in the mid 70s. Along with Jim Parry, Russell Crook, and Gary Calnek, he was co-author of the successful mainframe programs Ribbit  and its successor Treefrog , and wrote a master thesis on computer chess . At his time at Waterloo, Jonathan Schaeffer benefited from the presence of Ron Hansen, who generously gave him a copy of Ribbit's Fortran source code, which he used to learn how to write a chess program .
- Ron Hansen (1977). TREEFROG: a chess program. Master of Mathematics essay, Computer Science, University of Waterloo 
- Waterloo@50 (pdf) 2007
- Monty Newborn (1977). Summary of the ACM Sixth U.S. Computer Chess Championship. The Best of Creative Computing Volume 2, edited by David Ahl, hosted by AtariArchives.org » ACM 1975
- An Introduction to Computer Chess by Alejandro López-Ortiz, 1993
- Jonathan Schaeffer (1997, 2009). One Jump Ahead. 1. This Was Going to Be Easy, pp. 7
- Tony Marsland (1979). A bibliography of computer chess. Machine Intelligence 9, pdf