Cita APA (7a ed.)

Evans, I. O., & Hawkins, H. L. (1949). The Observer's book of geology: Describing the principal rocks, minerals and fossils. Warne.

Cita Chicago Style (17a ed.)

Evans, I. O., y H. L. Hawkins. The Observer's Book of Geology: Describing the Principal Rocks, Minerals and Fossils. London ; New York: Warne, 1949.

Cita MLA (9a ed.)

Evans, I. O., y H. L. Hawkins. The Observer's Book of Geology: Describing the Principal Rocks, Minerals and Fossils. Warne, 1949.