PUBLICATION HISTORY

  • Analog, December 1960.

  • Analog, April 1961. (British edition), p.35-53. Illustrated by Leo Summers.

  • Rulers of Men, edited by Hans Stefan Santesson. New York: Pyramid Books, 1965, pbk, p.135-159.

  • as: "Der K-Faktor" in: Die Mächtigen des Universums, edited by Hans Stefan Santesson. Munich: Heyne, 1970. Translated by Birgit Ress-Bohusch. [German]

  • 50 in 50, July 2001.