APA (7th ed.) Citation

Astor, J. J. (1999). A Journey in Other Worlds: A Romance of the Future. Project Gutenberg.

Chicago Style (17th ed.) Citation

Astor, John Jacob. A Journey in Other Worlds: A Romance of the Future. Project Gutenberg, 1999.

MLA (9th ed.) Citation

Astor, John Jacob. A Journey in Other Worlds: A Romance of the Future. Project Gutenberg, 1999.

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