New York: Bantam, (1992.) dj. SIGNED hardcover first edition - A "hard" science fiction novel on world building in six parts by Poul Anderson, Greg Bear, Gregory Benford, David Brin, Nancy Kress and Frederik Pohl (all Nebula award winning writers), edited by Silverberg. SIGNED by FOUR authors: by Silverberg on the title page, and by Gregory Benford, Nancy Kress and Greg Bear at their contributions. Notes on the authors. 292 pp. Wraparound dust jacket art by Stephen Youll. ISBN: 0-553-082299.