APA (7th ed.) Citation

Hilbert, D., & Townsend, E. J. (2005). The Foundations of Geometry. Project Gutenberg.

Chicago Style (17th ed.) Citation

Hilbert, David, and E. J. Townsend. The Foundations of Geometry. Project Gutenberg, 2005.

MLA (9th ed.) Citation

Hilbert, David, and E. J. Townsend. The Foundations of Geometry. Project Gutenberg, 2005.

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