Correspondence instruction in the United States; a study of what it is, how it functions, and what its potential may be - MacKenzie, Ossian; Christensen, Edward L.; Rigby, Paul H.; American Council on Education; National Commission on Accrediting (New York, McGraw-Hill, 1968)
Study sponsored by the American Council on Education and the National Commission on Accrediting.
Bibliography: p. 59-63.
Keywords: Correspondence schools and courses -- United States