Παραπομπή APA

Johnson, R. B., & Degraff, V. J. (1988). Principles of Engineering Geology. John Wiley.

Παραπομπή Chicago Style

Johnson, Robert. B., και V. Jerome Degraff. Principles of Engineering Geology. New Delhi: John Wiley, 1988.

Παραπομπή MLA

Johnson, Robert. B., και V. Jerome Degraff. Principles of Engineering Geology. John Wiley, 1988.