APA (7th ed.) Citation

Safari Tech Books Online, Lutz, M. A., & Ascher, D. C. (1999). Learning Python (First edition.). O'Reilly.

Chicago Style (17th ed.) Citation

Safari Tech Books Online, Mark Author Lutz, and David Contributor Ascher. Learning Python. First edition. [Place of publication not identified]: O'Reilly, 1999.

MLA (9th ed.) Citation

Safari Tech Books Online, et al. Learning Python. First edition. O'Reilly, 1999.