Bantilan, M C S and Anupama, K V and Joshi, P K  (2005) Assessing economic and environmental impacts of NRM technologies: an empirical application using the economic surplus approach.   In:  Natural resource management in agriculture: methods for assessing economic and environmental impacts.   CAB International, Wallingford, Oxon, UK, pp. 245-268.  ISBN 0-85199-828-3