APA (7th ed.) Citation
Whitehead, A. N., & Russell, B. Principia Mathematica.
Chicago Style (17th ed.) Citation
Whitehead, Alfred North, and Bertrand Russell. Principia Mathematica.
MLA (9th ed.) Citation
Whitehead, Alfred North, and Bertrand Russell. Principia Mathematica.
Warning: These citations may not always be 100% accurate.