a computer chess program written at the University of Waterloo by a team of the undergraduate students Ron Hansen, Russell Crook and Gary Calnek, and successor of Ribbit. Treefrog became runner up at the ACM 1975, losing from Chess 4.4 in the last round. It was written in Fortran and ran on a Honeywell 6080  36-bit mainframe computer.
- Ron Hansen (1977). TREEFROG: a chess program. Master of Mathematics essay, Computer Science, University of Waterloo