Does exactly what it says on the tin. A pocket-sized book that introduces the reader to the field of free improvisation, and gives routes into the music by suggesting things to listen out for, people to listen to and discussion around a variety of topics related to free improvisation.
When I first read it, it made me want to stand outside stations and hand copies of it to members of the public.
Suggested by Anton Hunter - manchester UK
University press of Chicago - URL LINK
University of Chicago Press