Interactive SETL by Gary Levin gary@clutx.clarkson.edu .
Current version: 3.0.
Binaries and source for MS-DOS , Macintosh , Unix , VAX / VMS .
[Clarkson U. "An Introduction to ISETL Version 1.9", G.M. Levin, Dept MCS, Clarkson U].
["Learning discrete mathematics with ISETL", Nancy Baxter. Ed. Gary Levin Dubinsky. Springer-Verlag, c.1989.]
(Apr 1994)