APA (7th ed.) Citation

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

Chicago Style (17th ed.) Citation

Birds, Steven, Ewan Klein, and Edward Loper. Natural Language Processing with Python. Beijing ; Cambridge [Mass.]: O'Reilly, 2009.

MLA (9th ed.) Citation

Birds, Steven, et al. Natural Language Processing with Python. O'Reilly, 2009.

Warning: These citations may not always be 100% accurate.