1. R. T. Burchill(1958 ). Studies on apple mildew . Ph.D. Thesis , University of Bristol.
2. STUDIES ON THE BIOLOGY OF ERYSIPHE GRAMINIS DC.
3. G. H. Freeman, and B. D. Bolas(1956 ). A method for the rapid determination of leaf areas in the field .Rep. E. Mulling Res. Sta. for 1955, p.104 .