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Emeralds. National Geographic Magazine

GEMS Ward, Fred Emeralds. National Geographic Magazine, July 1990
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Gemstones of East Africa

GEMS Keller, Peter C. AFR Gemstones of East Africa. Geoscience, 1992
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AZ Grand Canyon geology

GEO Price, L. Greer AZ Grand Canyon geology. Grand Canyon Association, 1999
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Franciscan and related rocks, and their significance in the geology of Western California

GEO Bailey, Edgar H. CA Franciscan and related rocks, and their significance in the geology of
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