APA (7th ed.) Citation

Newton, I., Newton, I., & Huygens, C. (1952). Mathematical principles of natural philosophy. Encyclopaedia Britannica.

Chicago Style (17th ed.) Citation

Newton, Isaac, Isaac Newton, and Christiaan Huygens. Mathematical Principles of Natural Philosophy. Chicago u.a: Encyclopaedia Britannica, 1952.

MLA (9th ed.) Citation

Newton, Isaac, et al. Mathematical Principles of Natural Philosophy. Encyclopaedia Britannica, 1952.