APA (7th ed.) Citation

Whitehead, A. N. (2012). An Introduction to Mathematics. Project Gutenberg.

Chicago Style (17th ed.) Citation

Whitehead, Alfred North. An Introduction to Mathematics. Project Gutenberg, 2012.

MLA (9th ed.) Citation

Whitehead, Alfred North. An Introduction to Mathematics. Project Gutenberg, 2012.

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