APA (7th ed.) Citation

Blackmar, F. W. (2009). History of Human Society. Project Gutenberg.

Chicago Style (17th ed.) Citation

Blackmar, Frank W. History of Human Society. Project Gutenberg, 2009.

MLA (9th ed.) Citation

Blackmar, Frank W. History of Human Society. Project Gutenberg, 2009.

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