AVON / AMERICAN PAPERBACK EDITION. Introduction by the editor plus the following stories: At the End of the Orbit (1961) by Arthur C. Clarke; On the Feasibility of Coal-Driven Power Stations (1956) by O. R. Frisch; A Feast of Demons (1958) by William Morrison; The Heart on the Other Side by George Gamow; Lenny [Susan Calvin (Robot)] (1958) by Isaac Asimov; The Singers (1956) by W. Grey Walter; The Invasion (1940) by Robert Willey; To Explain Mrs. Thompson (1951) by Philip Latham; Adrift on the Policy Level (1959) by Chandler Davis; The Black Cloud (Excerpt) (1957) by Fred Hoyle; Chain Reaction (1956) by Lyle by Boyd Ellanby; The Miracle of the Broom Closet (1952) by W. Norbert; Heavy Planet (1939) by Lee Gregor; The Test Stand (1955) by Lee Correy; Amateur in Chancery (1961) by George O. Smith; The Mark Gable Foundation (1961) by Leo Szilard.