A book by Isaac Asimov
The Door into Summer is a science fiction novel by Robert A. Heinlein, originally serialized in The Magazine of Fantasy & Science Fiction (October, November, December 1956, with covers and interior illustrations by Frank Kelly Freas) and published in hardcover in 1957. It is a fast-paced hard science fiction novel, with a key fantastic element, and romantic elements. In three separate Locus Magazine readers polls from 1975 to 1998, it was judged the 36th, the 29th, or the 43rd all-time best science-fiction novel.
The title was triggered by a remark that Heinlein's wife had made: in the novel, the protagonist's cat refuses to leave their house through any of its numerous doors when he sees snow on the ground: he is looking for The Door into Summer. Heinlein wrote the complete novel in only 13 days. No rewrite was needed, only some light editing that Heinlein did himself.