The Lonely Voice (1962) is a study of the short story form, written by Frank O'Connor.
Each chapter focuses on a different author: One of the work's major contributions is that of "the submerged population group" - a term that O'Connor uses to characterise those individuals who, for whatever reasons, are left on the fringes of society.
[1] The term was taken up again in the twenty-first century by Amit Chaudhuri to usefully characterise modernist writing in the Indian subcontinent.
[2] The book is seen by many critics as the first lengthy examination of the short story form, and it has been heralded by many writers as an influential work.
This article about a non-fiction book on literary criticism is a stub.