Gubelin, E..
Internal World of Gemstones: Documents from Space and Time / - Second Ed. / - London WC2B 6AB : Butterworth & Co. Ltd. , 1979 - p.234 :
0-408-00436-3
H19 / L9
Internal World of Gemstones: Documents from Space and Time / - Second Ed. / - London WC2B 6AB : Butterworth & Co. Ltd. , 1979 - p.234 :
0-408-00436-3
H19 / L9