 The screenplay was written primarily by Stanley Kubrick (qv) and  the novel primarily by Arthur C. Clarke (qv), each working  simultaneously and also providing feedback to the other. As the  story went through many revisions, changes in the novel were taken  over into the screenplay and vice versa. It was also unclear whether  film or novel would be released first; in the end it was the film.  Kubrick was to have been credited as second author of the novel, but  in the end was not. It is believed that Kubrick deliberately  withheld his approval of the novel as to not hurt the release of the  film.