APA-referens (7:e uppl.)

Costales, B., & Allman, E. (1997). Sendmail (Second revised and updated edition.). O'Reilly; Shroff Publishers & Distributors PVT.LTD..

Chicago-referens (17:e uppl.)

Costales, Bryan, och Eric Allman. Sendmail. Second revised and updated edition. Beijing ; Sebastopol, CA : Mumbai ; Calcutta: O'Reilly; Shroff Publishers & Distributors PVT.LTD., 1997.

MLA-referens (8:e uppl.)

Costales, Bryan, och Eric Allman. Sendmail. Second revised and updated edition. O'Reilly; Shroff Publishers & Distributors PVT.LTD., 1997.