L. David Allen is an American academic, formerly instructor in English at the University of Nebraska, and author of various critical and historical works about science fiction. His first book – written as a Cliffs Notes overview for classroom use – was the useful Science Fiction: An Introduction.
Another of the "yellowed-pages" S-F books on my bookshelf, from the 70's. This one is copyrighted 1973, so is a bit dated, takes one up from Jules Verne and H.G. Welles to "Dune" and "The Left Hand of Darkness" and all that. Should prove to be interesting. I'll letcha know.