APA (7th ed.) Citation

Smith, D. E. (2011). The Teaching of Geometry. Project Gutenberg.

Chicago Style (17th ed.) Citation

Smith, David Eugene. The Teaching of Geometry. Project Gutenberg, 2011.

MLA (9th ed.) Citation

Smith, David Eugene. The Teaching of Geometry. Project Gutenberg, 2011.

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