Proc GUIDE Intl, GUIDE 34, May 14, 1972, pp. 540–556 W.R. Brittenham and B.F. Melkun, "The Systems Programming Language Problem", Proceedings of the IFIP Working Conference on Machine Oriented Higher Level Languages, Trondheim, Norway, August 29–31, 1973, pp. 29–47. Amsterdam: North-Holland Publishing Co.; New York: American Elsevier, 1974. This paper explores the technical and psychological problems encountered in implementing PL/S. The language and compiler are described. The discussion that followed presentation of the paper is included. Gio Wiederhold and John Ehrman, "Inferred SYNTAX and SEMANTICS of PL/S", Proceedings of the SIGPLAN symposium on Languages for system implementation 1971, in SIGPLAN Notices 6(10) October 1971 Guide to PL/S II, International Business Machines Corp., 1974. GC28-6794-0 Note that this manual is very out of date with respect to the PL/X language in use today. PL/I programming language family PL S Systems programming languages IBM System/360 mainframe line