TREET
E.C. Haines, 1964. An experimental variant of LISP1.5,
implemented on the STRETCH computer. Basic structure was a
trinary tree.
["The TREET {Time-Sharing} System", H.A. Bayard et al, Proc
2nd Symp Symb and Alg Manip, ACM (Mar 1971)].
[Sammet 1969, pp.457-461].