1. Harrison, M. D., C. H. Livingston, and N. Oshima. 1965. Control of potato early blight in Colorado. I. Fungicidal spray schedules in relation to the epidimiology of the disease. Amer. Potato J. 42:319–327.
2. Horsfall, J. G. and R. W. Barratt. 1945. An improved system for measuring plant diseases. Phytopathology 35:655.
3. Lutman, B. F. 1911. Twenty years spraying for potato diseases. Potato diseases and the weather. Vt. Agr. Exp. Sta. Bull. 159:225–296.
4. Ohms, R. E. and H. S. Fenwick. 1961. potato early blight, symptoms, cause and control. Idaho Agr. Ext. Serv. Bull. 346.
5. Potter, H. S. and W. J. Hooker. 1960. Early blight of potato. Michigan Agr. Ext. Fact Sheet 573.