APA (7th ed.) Citation

Blackwood, A. (2011). The Promise of Air. Project Gutenberg.

Chicago Style (17th ed.) Citation

Blackwood, Algernon. The Promise of Air. Project Gutenberg, 2011.

MLA (9th ed.) Citation

Blackwood, Algernon. The Promise of Air. Project Gutenberg, 2011.

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