Willey, R W and Natarajan, M and Reddy, M S and Rao, M R and Nambiar, P T C and Kannaiyan, J and Bhatnagar, V S  (1983) Intercropping studies with annual crops.  In: Better Crops for Food, Ciba Foundation Symposium 97, 14-16 Sept 1982, Pitman, London,Uk.