Cita APA (7th ed.)

Trahan, M., & Gray, P. (1991). Focus on psychology: A guide to mastering Peter Gray's psychology. Worth.

Cita Chicago (17th ed.)

Trahan, Mary, i Peter Gray. Focus on Psychology: A Guide to Mastering Peter Gray's Psychology. New York: Worth, 1991.

Cita MLA (9th ed.)

Trahan, Mary, i Peter Gray. Focus on Psychology: A Guide to Mastering Peter Gray's Psychology. Worth, 1991.