1. Whitelaw, E. W., and Perera, S. F. H., Report of the Commission of the Rubber Industry in Ceylon. Ceylon Sessional Paper 18 28 (1947).
2. Planters' Bull. Rubber Res. Inst. Malaya, N. S., No. 18, 49 (1955).
3. Hewitt, E. J., “Sand and Water Culture Methods used in the Study of Plant Nutrition” (Commonwealth Agricultural Bureau, 1952).