APA (7th ed.) Citation

Twaddell, W. F. (1968). The English verb auxiliaries (2. ed., 3. print.). Brown Univ. Press.

Chicago Style (17th ed.) Citation

Twaddell, William F. The English Verb Auxiliaries. 2. ed., 3. print. Providence, RI: Brown Univ. Press, 1968.

MLA (9th ed.) Citation

Twaddell, William F. The English Verb Auxiliaries. 2. ed., 3. print. Brown Univ. Press, 1968.