for Planet demonstrate his reservations about the advance of technology, in particular "The Golden Apples of the Sun" (November 1953), and "A Sound of Thunder" (January 1954, reprinted from the June 28, 1952 issue of Collier's Weekly). Bradbury's work in Planet Stories is regarded by one pulp historian, Tim de Forest, as "the magazine's most important contribution to the genre". Several other well-known writers appeared in Planet Stories, including Isaac Asimov, Clifford Simak, James Blish, Fredric Brown and Damon Knight. Asimov's story, originally titled "Pilgrimage", appeared in 1942; Asimov had been unable to sell the piece elsewhere, and rewrote it numerous times for different editors, adding a religious element at John Campbell's request, and removing it again when Malcolm Reiss asked for further changes. Reiss bought it but changed the name to "Black Friar of the Flame". Jerome Bixby, who took over as editor in 1950, was a published writer and was knowledgeable about sf, though he had primarily written western fiction. In his short tenure he did much to improve the magazine, persuading the established writers to produce better material and finding unusual variations on the interplanetary adventure theme such as Poul Anderson's "Duel on Syrtis" in March 1951, about an Earthman tracking an alien on Mars, and Theodore Sturgeon's "The Incubi on Planet X", about aliens who kidnap Earth women. After Bixby's departure in 1952, Planet Stories major contribution to the genre was the discovery of Philip K. Dick, whose first sale, "Beyond Lies the Wub", appeared in the July 1952 issue. Dick went on to sell another four stories to Planet Stories over the next two years, including "James P. Crow", in which a human suffers discrimination in a world of robots. Planet Stories clearly targeted a young readership, and the simultaneous launch in 1939 of Planet Comics may have been instrumental in attracting young readers to science fiction, but Ashley suggests that it is more likely that Planet Stories attracted experienced readers of the genre who "still yearned for the early days of sf". Critic and sf historian Thomas Clareson has commented that "Planet seemed to look backward towards the 1930s and earlier", an impression that was strengthened by the extensive use of interior artwork by Frank Paul, who had been the cover artist for the early Gernsback magazines in the 1920s. Paul's distinctive style was strongly associated with the early years of the field. The