APA (7th ed.) Citation

Budrys, A., & Dongen, H. R. v. (2008). Citadel. Project Gutenberg.

Chicago Style (17th ed.) Citation

Budrys, Algis, and H. R. van Dongen. Citadel. Project Gutenberg, 2008.

MLA (9th ed.) Citation

Budrys, Algis, and H. R. van Dongen. Citadel. Project Gutenberg, 2008.

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