Gelfand, H., & Walker, C. J. (2002). Mastering APA Style: Student's workbook and training guide. American Psychological Association.

Gelfand, Harold, and Charles J. Walker. Mastering APA Style: Student's Workbook and Training Guide. Washington, D.C: American Psychological Association, 2002.

Gelfand, Harold, and Charles J. Walker. Mastering APA Style: Student's Workbook and Training Guide. American Psychological Association, 2002.