1. Cochran, W. G., and Cox, G. M. (1950). Experimental designs. Wiley, New York.
2. Pearce, S. C.(1953). Field experimentation with fruit trees and other perennial plants.T.C. 23 Comm. Bur. Hort. East Mailing, p. 70.
3. Uganda Department of Agriculture(1959). Annual Report for 1958, para. 169.