APA (7th ed.) Citation

Marden, O. S. (2006). Cheerfulness as a Life Power. Project Gutenberg.

Chicago Style (17th ed.) Citation

Marden, Orison Swett. Cheerfulness as a Life Power. Project Gutenberg, 2006.

MLA (9th ed.) Citation

Marden, Orison Swett. Cheerfulness as a Life Power. Project Gutenberg, 2006.

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