Few writers/editors influenced Marvel more than Mark Gruenwald (1953-1996). Famed for pioneering work on Official Handbook of the Marvel Universe and his magnum opus Squadron Supreme, he also wrote a hundred-plus-issue run of Captain America; multiple Marvel Two-in-One sagas; and several miniseries, including Contest of Champions, the first of Marvel's multi-hero sagas. He explored the Marvel Universe's ancient history in a series of What If? backup stories he also penciled. Glenn Herdling worked as an assistant editor on Amazing Spider-Man starting in 1987, helping the title enjoy a period of record-breaking success. He was later promoted to editorial director of Marvel's custom-publishing division and designed the company's first comic-book-style annual reports. His writing career began on Namor. The extensive research of comics historian Peter Sanderson was vital for both the Official Handbook of the Marvel Universe and Who's Who in the DC Universe. As well as chronicling the history of the House of Ideas in Marvel Saga, Sanderson has written multiple books on the subject, including Marvel Universe and The Marvel Encyclopedia. Keith Pollard drew simultaneous runs on three of Marvel's longest-running titles- Amazing Spider-Man, Fantastic Four and Thor, including Roy Thomas and Mark Gruenwald's ""Eternals Saga."" During the 1990s, he singlehandedly penciled hundreds of characters for the Official Handbook of the Marvel Universe- Master Edition.