There's been a lot of "worthy" books mentioned here (
I'll mention a book that I doubt would ever be present on such a list but which I return to time after time: Kevin MacDonnell's "Freelance Photographers' Britain
". (ISBN 0-907297-11-0)
MacDonnell was a working photographer and writer who's career spanned the 'thirties to the 'eighties. He only published half a dozen books or so and this is by far the one I like best.
Despite the title, I think this little gem tells more about the how and why of taking pictures than any three of the rest.
Oh yes, and anything by our own Roger Hicks.