Westermann, D., & Ward, I. C. (1933). Practical phonetics for students of African languages. Published for the International Institute of African Languages & Cultures by Oxford University Press, H. Milford.

Westermann, Diedrich, and Ida C. Ward. Practical Phonetics for Students of African Languages. London: Published for the International Institute of African Languages & Cultures by Oxford University Press, H. Milford, 1933.

Westermann, Diedrich, and Ida C. Ward. Practical Phonetics for Students of African Languages. Published for the International Institute of African Languages & Cultures by Oxford University Press, H. Milford, 1933.