Studies on the cytoplasmic granules stainable with carcinogenic azo-dye, o-amino-azo-toluene. I. Classification of cytoplasmic granules in amphibian erythrocytes and their cytochemical natures Nagatani, Y. Japanese Jour Zool 12(2): 163-177 1958 https://eurekamag.com/research/025/575/025575635.php