APA (7th ed.) Citation

Hartshorne, H. (2010). 1931: A Glance at the Twentieth Century. Project Gutenberg.

Chicago Style (17th ed.) Citation

Hartshorne, Henry. 1931: A Glance at the Twentieth Century. Project Gutenberg, 2010.

MLA (9th ed.) Citation

Hartshorne, Henry. 1931: A Glance at the Twentieth Century. Project Gutenberg, 2010.

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