APA (7th ed.) Citation

Humboldt, A. v., & Otté, E. C. (2005). Cosmos: A Sketch of the Physical Description of the Universe, Vol. 1. Project Gutenberg.

Chicago Style (17th ed.) Citation

Humboldt, Alexander von, and E. C. Otté. Cosmos: A Sketch of the Physical Description of the Universe, Vol. 1. Project Gutenberg, 2005.

MLA (9th ed.) Citation

Humboldt, Alexander von, and E. C. Otté. Cosmos: A Sketch of the Physical Description of the Universe, Vol. 1. Project Gutenberg, 2005.

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