APA aipamena

Simpson, G. G. (1979). Earth history at the century mark of the U.S. Geological Survey.

Chicago Style aipamena

Simpson, George Gaylord. Earth History At the Century Mark of the U.S. Geological Survey. 1979.

MLA aipamena

Simpson, George Gaylord. Earth History At the Century Mark of the U.S. Geological Survey. 1979.