Cita APA (7a ed.)

Costales, B., & Allman, E. (2003). Sendmail (3rd ed.). O'Reilly.

Cita Chicago Style (17a ed.)

Costales, Bryan, y Eric Allman. Sendmail. 3rd ed. Sebastopol, CA: O'Reilly, 2003.

Cita MLA (8a ed.)

Costales, Bryan, y Eric Allman. Sendmail. 3rd ed. O'Reilly, 2003.