Cita APA (7th ed.)

Philip Lief Group, Princeton Language Institute, & O'Connor, J. (1994). 21st century guide to pronunciation. Dell.

Cita Chicago (17th ed.)

Philip Lief Group, Princeton Language Institute, i Joyce O'Connor. 21st Century Guide to Pronunciation. New York: Dell, 1994.

Cita MLA (9th ed.)

Philip Lief Group, et al. 21st Century Guide to Pronunciation. Dell, 1994.