APA (7th ed.) Citation

Cather, W. (2007). O Pioneers! Project Gutenberg.

Chicago Style (17th ed.) Citation

Cather, Willa. O Pioneers! Project Gutenberg, 2007.

MLA (9th ed.) Citation

Cather, Willa. O Pioneers! Project Gutenberg, 2007.

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