"1977"^^ . . . . "Bulla & Cheng (1977)" . "Bulla, L. A. & Cheng, T. C. 1977. Comparative Pathobiology. Volume 2. Systematics of the Microsporidia. Plenum Press. New-York and London. 510 pp. " . "Bulla & Cheng (1977)" . "1977"^^ .