APA (7th ed.) Citation

Schwartz, A., & Garfinkel, S. (1998). Stopping spam. O'Reilly.

Chicago Style (17th ed.) Citation

Schwartz, Alan, and Simson Garfinkel. Stopping Spam. Sebastopol, CA: O'Reilly, 1998.

MLA (9th ed.) Citation

Schwartz, Alan, and Simson Garfinkel. Stopping Spam. O'Reilly, 1998.