Librarian Note: There is more than one author in the Goodreads database with this name. Harry Harrison (born Henry Maxwell Dempsey) was an American science fiction author best known for his character the The Stainless Steel Rat and the novel Make Room! Make Room! (1966), the basis for the film Soylent Green (1973). He was also (with Brian W. Aldiss) co-president of the Birmingham Science Fiction Group. Excerpted from Wikipedia.

Colin Derek Ivor Kapp was a popular UK science fiction author, but one who never became a success in the USA. He was active, though not prolific, as an author in the 1960s through to the 1980s. He is best known for his "Unorthodox Engineers" stories, which recount an eccentric group of engineers, who accomplish impossible feats of engineering against all odds. Pen names: Colin Papp, Colin Capp.