This is a very good anthology of fifteen science fiction short novels, or four novelettes and eleven novellas according to the SFWA definitions as they apply to wordage. In either case, it's a long, massive book, and I was pleased when the SF Book Club released an affordable edition in 1981. Greenberg and Silverberg selected stories dating from 1941 (Heinlein's By His Bootstraps) to 1977 (Varley's Equinoctial) and struck a nice balance of famous classics and lesser-known works, as well as famous (Asimov, Clarke, Sturgeon) and less well-known authors (DeVet, MacLean, Guin). The contents are dominated by stories from Astounding SF magazine (five stories), with two from Galaxy, and one each from Infinity, If, F & SF, true pulp Thrilling Wonder Stories, Worlds of Tomorrow, the unlikely-named Two Complete Science Adventure Books, and two of the most recent from original book anthologies. I especially enjoyed Sturgeon's The Golden Helix, Delany's The Star Pit, editor Silverberg's Born with the Dead, Blish's A Case of Conscience, Chandler's Giant Killer, Heinlein's By His Bootstraps, Cordwainer Smith's On the Storm Planet, Tiptree's Houston, Houston, Do You Read? It was neat they included a Jack Vance that wasn't The Dragon Masters or The Last Castle (it was The Miracle Workers), and I remember being especially impressed with Wyman Guin's Beyond Bedlam. It's a great collection of old (and a few older!) classics.