APA (7th ed.) Citation

Robinson, F., & Robinson, C. H. (2007). Letters to His Friends. Project Gutenberg.

Chicago Style (17th ed.) Citation

Robinson, Forbes, and Charles H. Robinson. Letters to His Friends. Project Gutenberg, 2007.

MLA (9th ed.) Citation

Robinson, Forbes, and Charles H. Robinson. Letters to His Friends. Project Gutenberg, 2007.

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