APA (7th ed.) Citation

Keeler, J. E. (2011). Photographs of Nebulæ and Clusters Made with the Crossley Reflector. Project Gutenberg.

Chicago Style (17th ed.) Citation

Keeler, James Edward. Photographs of Nebulæ and Clusters Made with the Crossley Reflector. Project Gutenberg, 2011.

MLA (9th ed.) Citation

Keeler, James Edward. Photographs of Nebulæ and Clusters Made with the Crossley Reflector. Project Gutenberg, 2011.

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