Harry Harrison has used various pseudonyms for some of his stories; these include Hank Dempsey, Felix Boyd, Wade Kaempfert, Cameron Hall and Philip St. John. He is sometimes credited with stories written under the "Harrison Denmark" name, however that is the pseudonym of Roger Zelazny, not Harry Harrison.
Harry Harrison: I know writers who start a story with no idea how it will end; I would rather die first. I am a firm back-plotter and must know the ending before I begin, then expend writing energy disguising the fact that I always know what is coming next.
Harry Harrison: Writing is a fragile act. When one is pulling language, thoughts, ideas out of thin air, or the turgid subconscious, any disturbance disturbs. ...I know of no serious writer who does not need his solitude, his sitting and thinking time, in addition to his writing time.