Pohl stopped being Asimov's agent—the only one the latter ever had—when he became editor from 1939 to 1943 of two pulp magazines, "Astonishing Stories" and "Super Science Stories". Stories by Pohl often appeared in these science-fiction magazines, but never under his own name. Work written in collaboration with Cyril M. Kornbluth was credited to S. D. Gottesman or Scott Mariner; other collaborative work (with any combination of Kornbluth, Dirk Wylie, or Robert A. W. Lownes) was credited to Paul Dennis Lavond. For Pohl's solo work, stories were credited to James MacCreigh (or for one story only, Warren F. Howard.) Works by "Gottesman", "Lavond", and "MacCreigh" continued to appear in various science-fiction pulp magazines throughout the 1940s.