Free fiction: Klint Finley's "Evolution of the mutant in popular fiction" at Renegade Futurist links some stories
Lists some relevant works, several of them with download links.
Among the included links is one to an online copy of Henry Kuttner & C L Moore's collection "Mutant" (as by Lewis Padgett). Very readable stories involving uncomfortable living side-by-side of normal humans & a telepathic branch of humanity. These stories are a reaction to Hitler's brand of racism, & occasionally the anger of authors becomes very visible.