In Comics
Amazing Spider-Man #2 (May, 1963)
The X-Men #49 - Who Dares Defy The Demi-Men?
Base
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Serval Industries, Virginia; formerly X-Factor Investigations Headquarters, Starjammer; Xavier Institute for Higher Learning, Salem Center, Westchester County, New York; Genosha; X-Factor HQ, Washington D.C., Maryland; Mutant Research Center, Muir Island;