Stableford, Brian. "Parallel Worlds"
Comments: Encyclopedia entry citing various titles.
Published: In The Encyclopedia of Science Fiction, 2nd ed. (eds. John Clute and Peter Nicholls), Orbit 1993 (1857231244), 1999 (1857238974w88 android); St. Martin's 1993 (0312096186BUY); St. Martin's/Griffin 1995 (031213486XBUY); SFBC 1996.
Published: Revision of "Parallel Worlds", in The Encyclopedia of Science Fiction: An Illustrated A to Z (ed. Peter Nicholls), Granada 1979 (0246110201), v.t. The Science Fiction Encyclopedia, Doubleday/Dolphin 1979 (0385147430).