K. . Njunwa, G. Mwaiko, B. Kilonzo, and J. . Mhina, “Studies on the Seasonal Patterns of Rodent, Flea and Plague Outbreaks in the Western Usambara Mountains, North-East Tanzania”, Tanz Vet J, vol. 7, no. 2, pp. 16–27, Mar. 1985.