1. Chapman, C. I. & C. G. Finch, 1961. Summer lettuce variety trials 1955–1957. J. natn. Inst. agric. Bot. 9: 57–71.
2. Cochran, W. G. & G. M. Cox, 1950. Experimental designs. John Willy & Sons, Inc. New York, London. p. 307.
3. Crute, I. R. & A. A. Davis, 1977. Specificity of Bremia lactucae from Lactuca sativa. Trans. Br. mycol. Soc. 69: 405–410.
4. Crute, I. R. & P. L. Gordon, 1980. Downy mildew of lettuce
5. Integrated control. Rep. nat. Veg. Res. Stn. for 1979: 75.