Published by the Elmwood Institute, Berbeley, CA 94705. Edited by "Systems Education Research", Olympia, Wa 98502, first édition, winter 1990 104 pages.
Ed. PUF. 1998, ISBN 2-13-049671-7, 444 pages.
PUF. "Que Sais-je ?" n° 3468, ISBN 2 13 049840 X, 127 pages.