APA (7th ed.) Citation

Henn, U., & Bank, H. (1992). Gemstones of the feldspar group. The Canadian gemmologist, 13, .

Chicago Style (17th ed.) Citation

Henn, Ulrich, and Hermann Bank. "Gemstones of the Feldspar Group." The Canadian Gemmologist 13 (1992).

MLA (9th ed.) Citation

Henn, Ulrich, and Hermann Bank. "Gemstones of the Feldspar Group." The Canadian Gemmologist, vol. 13, 1992.

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