APA (7th ed.) Citation

Alcott, L. M. (2005). The Mysterious Key and What It Opened. Project Gutenberg.

Chicago Style (17th ed.) Citation

Alcott, Louisa May. The Mysterious Key and What It Opened. Project Gutenberg, 2005.

MLA (9th ed.) Citation

Alcott, Louisa May. The Mysterious Key and What It Opened. Project Gutenberg, 2005.

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