APA (7th ed.) Citation

Roberts, C. G. D. (2010). The Secret Trails. Project Gutenberg.

Chicago Style (17th ed.) Citation

Roberts, Charles G. D. The Secret Trails. Project Gutenberg, 2010.

MLA (9th ed.) Citation

Roberts, Charles G. D. The Secret Trails. Project Gutenberg, 2010.

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