Cita APA

Lyell, C., & Secord, J. A. (1997). Principles of geology. Penguin Books.

Chicago Edition Citation

Lyell, Charles, i James A. Secord. Principles of Geology. London ; New York: Penguin Books, 1997.

Cita MLA

Lyell, Charles, i James A. Secord. Principles of Geology. Penguin Books, 1997.