Hurlbut, C. S., & Kammerling, R. C. (1993). Gemología (2a ed.). Omega.
Chicago Style (17th ed.) CitationHurlbut, Cornelius Searle, and Robert C. Kammerling. Gemología. 2a ed. Barcelona: Omega, 1993.
MLA (9th ed.) CitationHurlbut, Cornelius Searle, and Robert C. Kammerling. Gemología. 2a ed. Omega, 1993.