Cita APA (7th ed.)
Johnson, R. B., & Degraff, J. V. (1988). Principles of Engineering Geology. John Wiley & Sons.
Cita Chicago (17th ed.)
Johnson, Robert B., i Jerome V. Degraff. Principles of Engineering Geology. New Delhi: John Wiley & Sons, 1988.
Cita MLA (9th ed.)
Johnson, Robert B., i Jerome V. Degraff. Principles of Engineering Geology. John Wiley & Sons, 1988.
Atenció: Aquestes cites poden no estar 100% correctes.