Cita APA (7a ed.)

Costales, B., & Allman, E. (1993). Sendmail. O'Reilly & Associates, Inc.

Cita Chicago Style (17a ed.)

Costales, Bryan, y Eric Allman. Sendmail. Sebastopol, Calif: O'Reilly & Associates, Inc, 1993.

Cita MLA (9a ed.)

Costales, Bryan, y Eric Allman. Sendmail. O'Reilly & Associates, Inc, 1993.