50 GREATEST SF books by Abe: Here are the criteria used. One book per author, so that was hard on the big three of science fiction – Robert Heinlein, Isaac Asimov and Arthur C Clarke, who each have multiple classic titles to their name. Attempt to show as many sub-genres of science fiction and plot themes as possible. Include early stories that influenced the genre as a whole and launched popular themes, even if those books appear a bit dated today. A well thought out list w/ explanation.