APA (7th ed.) Citation

Hubble, E. (1937). The observational approach to cosmology. The Clarendon press.

Chicago Style (17th ed.) Citation

Hubble, Edwin. The Observational Approach to Cosmology. Oxford: The Clarendon press, 1937.

MLA (9th ed.) Citation

Hubble, Edwin. The Observational Approach to Cosmology. The Clarendon press, 1937.

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