Gaya APA

HURLBUT, C, S, J, K, R, C. (1991). Gemology. Second edition . : John Wiley & Sons Inc.

Gaya MLA

HURLBUT, Cornelius, S., Jr.;, KAMMERLING,, Robert, C. "Gemology. Second edition". : John Wiley & Sons Inc, 1991. Buku.