APA (7th ed.) Citation

Bird, S., Klein, E., & Loper, E. (2009). Natural language processing with Python (First edition.). O'Reilly.

Chicago Style (17th ed.) Citation

Bird, Steven, Ewan Klein, and Edward Loper. Natural Language Processing with Python. First edition. Beijing ; Cambridge, Mass.: O'Reilly, 2009.

MLA (8th ed.) Citation

Bird, Steven, et al. Natural Language Processing with Python. First edition. O'Reilly, 2009.