APA (7th ed.) Citation

Adler, F. (2007). The Essentials of Spirituality. Project Gutenberg.

Chicago Style (17th ed.) Citation

Adler, Felix. The Essentials of Spirituality. Project Gutenberg, 2007.

MLA (9th ed.) Citation

Adler, Felix. The Essentials of Spirituality. Project Gutenberg, 2007.

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