Ray Bradbury is a science fiction writer, but his mainstream success and popular profile have led to some unusual assessments of his work. In Clute and Nicholls's The Encyclopaedia of Science Fiction, Bradbury is defined as a “fantasy and horror” writer rather than a “science fiction” one, for instance, perhaps because Bradbury has tended to write self-consciously in a “literary” mode, and perhaps because of his “crossover” success (the majority of his stories were not published in generic SF magazines, for instance). His longevity has also been something of a critical conundrum, although it is usually suggested that his best work is from the 1950s, comprising the short stories collected in The Illustrated …
Baker, Brian. "Ray Bradbury". The Literary Encyclopedia. First published 27 June 2008; last revised 30 November -1.
[http://www.litencyc.com/php/speople.php?rec=true&UID=529, accessed 26 April 2015.]