Harker, A. (1954). Petrology for students: An introduction to the study of rocks under the microscope (8th ed. rev.). University Press.

Harker, Alfred. Petrology for Students: An Introduction to the Study of Rocks Under the Microscope. 8th ed. rev. Cambridge [Eng.]: University Press, 1954.

Harker, Alfred. Petrology for Students: An Introduction to the Study of Rocks Under the Microscope. 8th ed. rev. University Press, 1954.