APA (7th ed.) Citation

Keller, P. C. (1990). Gemstones and their origins. Van Nostrand Reinhold.

Chicago Style (17th ed.) Citation

Keller, Peter C. Gemstones and Their Origins. New York: Van Nostrand Reinhold, 1990.

MLA (9th ed.) Citation

Keller, Peter C. Gemstones and Their Origins. Van Nostrand Reinhold, 1990.

Warning: These citations may not always be 100% accurate.