Garfinkel, Simson; Spafford, Gene; Schwartz, Alan (December 15, 2003). Practical UNIX and Internet Security. "O'Reilly Media, Inc.". ISBN9780596003234. Archived from the original on February 5, 2021. Retrieved December 25, 2020 – via Google Books.
Garfinkel, Simson; Spafford, Gene; Schwartz, Alan (December 15, 2003). Practical UNIX and Internet Security. "O'Reilly Media, Inc.". ISBN9780596003234. Archived from the original on February 5, 2021. Retrieved December 25, 2020 – via Google Books.