Jarvis, Peter, ed. An international dictionary of adult and continuing education. A good general dictionary for troublesome terms and definitions. Tuijnman, Albert C., ed. International encyclopedia of adult education and training, 2nd edition.
Articles are thorough, with good bibliographies.
One of the best starting points in searching the adult education literature. Titmus, Colin J., ed. Pergamon Press, 1989. Most adult education literature can be found in the Library of Congress call number area LC 5201-LC 6251, although some items may be in other call number areas. 1988 Collins, Michael.