K.  Wada, ?Experimental biological studies on the occurrence of yellow color in pearls?, Bulletin of the National Pearl Research Laboratory, vol. 14, pp. 1765-1820, 1969.

K.  Wada, ?Experimental biological studies on the occurrence of yellow color in pearls?, Bulletin of the National Pearl Research Laboratory, vol. 14, pp. 1765-1820, 1969.