1. BLEASDALE, J. K. A. (1963). The bed system of carrot growing.Short Term Leaflet No. 27, Ministry of Agriculture, Fisheries & Food, London.
2. STECKEL, J. R. A. and GRAY, D. (1980). Fluid drilling onions.Report of the National Vegetable Research Station, Wellesbourne for 1979, 100.