Dyfyniad APA

Gemological Institute of America & American Gem Society. Gems & gemology. Gemological Institute of America.

Dyfyniad Arddull Chicago

Gemological Institute of America and American Gem Society. Gems & Gemology. Santa Monica [etc.]: Gemological Institute of America.

Dyfyniad MLA

Gemological Institute of America and American Gem Society. Gems & Gemology. Gemological Institute of America.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.