APA (7th ed.) Citation

Shoghi, E. (2006). Citadel of Faith. Project Gutenberg.

Chicago Style (17th ed.) Citation

Shoghi, Effendi. Citadel of Faith. Project Gutenberg, 2006.

MLA (9th ed.) Citation

Shoghi, Effendi. Citadel of Faith. Project Gutenberg, 2006.

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