APA (7th ed.) Citation

Snell, R. J. (2013). The Secret Mark An Adventure Story for Girls. Project Gutenberg.

Chicago Style (17th ed.) Citation

Snell, Roy J. The Secret Mark An Adventure Story for Girls. Project Gutenberg, 2013.

MLA (9th ed.) Citation

Snell, Roy J. The Secret Mark An Adventure Story for Girls. Project Gutenberg, 2013.

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