fantasy". A.E. van Vogt, a frequent Astounding contributor, appeared in the final issue with "The Book of Ptath" (later expanded into a novel). Isaac Asimov, despite multiple attempts to write for Unknown, never appeared in the magazine. On his sixth attempt, he sold "Author! Author!" to Campbell, but the magazine was canceled before it could appear. It eventually appeared in the anthology The Unknown Five. In addition to the overlap between the writers of Unknown and Astounding, there was a good deal of overlap between their readerships: Asimov records that during the war, he read only these two magazines. SF historian Paul Carter has argued that the spectrum of fantastic fiction from Weird Tales through Unknown to Astounding was far less cleanly separated than is sometimes assumed: many stories in the early science fiction magazines such as Wonder Stories were more like the works of Edgar Allan Poe than they were tales of scientific imagination. Fritz Leiber's first published story was "Two Sought Adventure", which appeared in the August 1939 issue of Unknown; this was the first story in his long-running Fafhrd and the Gray Mouser series about a pair of adventurers in a sword and sorcery setting. Four more Fafhrd and the Gray Mouser stories appeared in Unknown in as many years, and Leiber's novel Conjure Wife, about a man who discovers that all women are secretly witches, was the lead story in the April 1943 issue. The protagonist, a university professor, "is forced to abandon scepticism and discover the underlying equations of magic, via symbolic logic", in critic David Langford's description. Leiber also contributed "Smoke Ghost" in October 1941, described by Ashley as "arguably the first seriously modern ghost story". Another writer whose first story appeared in Unknown was James H. Schmitz, whose "Greenface" appeared in the August 1943 issue. Other notable stories that appeared in Unknown include Jack Williamson's "Darker Than You Think" (December 1940), which provides a scientific basis for a race of werewolves living undetected alongside human beings. Expanded into a novel in 1948, it remains Williamson's best-known fantasy, and SF historian Malcolm Edwards comments that the two protagonists' relationship is "depicted with a tortured (and still haunting) erotic frankness unusual in genre literature of the 1940s". In addition to the Harold Shea pieces, de Camp published several other well-received stories, including "The Wheels of If" (October 1940) and "Lest Darkness Fall" (December 1939), an