1. Dobell, C., Arch. Protistenkunde, 26, 117 (1912).
2. Zuelzer, M., in Prowazek's, “Handb. d. path. Protozoen”, 3, 1628 (1923); see also Noguchi, H., in Jordan and Falk's, “Newer Knowledge of Bacteriology and Immunology” (1928).
3. Gray, J., Nature, 168, 929 (1951).