APA (7th ed.) Citation

Gilbert, R. E., & Stone, D. (2010). A Thought For Tomorrow. Project Gutenberg.

Chicago Style (17th ed.) Citation

Gilbert, Robert E., and David Stone. A Thought For Tomorrow. Project Gutenberg, 2010.

MLA (9th ed.) Citation

Gilbert, Robert E., and David Stone. A Thought For Tomorrow. Project Gutenberg, 2010.

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