The clone

Isaac Asimov, Martin H. Greenberg, Charles G. Waugh, Theodore L. Thomas, Alan Edward Nourse, Robert Sheckley, Terry Carr, Poul Anderson, James Blish, Arthur C. Clarke, Fritz Leiber, Alexei Panshin, Larry Niven, Robert F. Young, Duncan Lunan

Isaac Asimov, Martin H. Greenberg, Charles Waugh, Robert Silverberg, Lloyd Biggle Jr, J.-H. Rosny, aîné, Theodore L. Thomas, William Tenn, Roger Zelazny, F. L. Wallace, A. E. van Vogt, Philip José Farmer, Murray Leinster, Michael Shaara

Isaac Asimov, George Zebrowski, Martin H. Greenberg, James E. Gunn, Steven Weinberg, Stanisław Lem, Clifford D. Simak, Gregory Benford, Laurence Manning, Brian W. Aldiss, A. E. van Vogt, Carl Sagan, Arthur C. Clarke, Raymond Z. Gallun, Eric Frank Russell, H. G. Wells, Chad Oliver, Theodore L. Thomas, Richard McKenna, Ian Watson

Isaac Asimov, Martin H. Greenberg, Charles Waugh, Robert Silverberg, Theodore L. Thomas, Marion Gross, Lawrence L. LeShan

Charles L. Harness, Theodore L. Thomas

Isaac Asimov, Martin H. Greenberg, J. G. Ballard, James White, R. A. Lafferty, Poul Anderson, Fritz Leiber, Mark Clifton, Theodore L. Thomas, Mack Reynolds, Harry Harrison, Theodore Sturgeon, Cordwainer Smith, Christopher Anvil, Gordon R. Dickson

Max Williams, Theodore L. Thomas, Rosel George Brown, E. Mittleman, Joseph Wesley