Mackay, I. (1987). Phonetics: The Science of Speech Production (2nd edition). A College-Hill Publication: Little, Brown and Company. Boston. [as "P. Ladefoged" above, these are rich & comprehensive discussions of phonology].
Roach, P. (1991). English Phonetics and Phonology: A Practical Course. New York/ London/ Melbourne/ Sydney: Cambridge University Press.
Swan, M., & Smith, B. (1987). Learner English: A teacher's guide to interference and other problems. Cambridge: Cambridge University Press.