Gunathilaka, R.P.D.; Jayasundera, J.M.M.A.; Fernandopulle, M.N.D.(Faculty of Agriculture and Plantation Management, Wayamba University of Sri Lanka, Makandura, 2005)
Pushpakumari, O.P.G.; Siriwardhane, K.P.D.; Rathnayake, R.H.M.K.(Faculty of Agriculture and Plantation Management,Wayamba University of Sri Lanka, Makandura, 2006)