Frailey, L., Mamchak, S. P., & Mamchak, S. R. (1989). Handbook of business letters/3e (3rd ed.). Super book housse.
Chicago Style aipamenaFrailey, L.E, Susan P. Mamchak, and Steven R. Mamchak. Handbook of Business Letters/3e. 3rd ed. Bombay: Super book housse, 1989.
MLA aipamenaFrailey, L.E, et al. Handbook of Business Letters/3e. 3rd ed. Super book housse, 1989.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.