APA (7th ed.) Citation

Beale, C. W. (2013). The Secret of the Earth. Project Gutenberg.

Chicago Style (17th ed.) Citation

Beale, Charles Willing. The Secret of the Earth. Project Gutenberg, 2013.

MLA (9th ed.) Citation

Beale, Charles Willing. The Secret of the Earth. Project Gutenberg, 2013.

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