APA (7th ed.) Citation

Steele, C. K. (2005). The Diamond Cross Mystery Being a Somewhat Different Detective Story. Project Gutenberg.

Chicago Style (17th ed.) Citation

Steele, Chester K. The Diamond Cross Mystery Being a Somewhat Different Detective Story. Project Gutenberg, 2005.

MLA (9th ed.) Citation

Steele, Chester K. The Diamond Cross Mystery Being a Somewhat Different Detective Story. Project Gutenberg, 2005.

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