Keller, P. C. (1990). Gemstones and their origins. Van Nostrand Reinhold.
Chicagoスタイル(17版)引用形式Keller, Peter C. Gemstones and Their Origins. New York: Van Nostrand Reinhold, 1990.
MLA(9版)引用形式Keller, Peter C. Gemstones and Their Origins. Van Nostrand Reinhold, 1990.
警告: この引用は必ずしも正確ではありません.