Siriwardana, N.S.B.; Zuhry, A.L.M.; Weerakkody, W.J.S.K.(Faculty of Agriculture and Plantation Management,Wayamba University of Sri Lanka, Makandura, 2013)
Deepika, U.K.D.K.; Senevirathne, P.; Nayanakantha, C.; Wickramasinghe, W.M.E.P.(Faculty of Agriculture and Plantation Management, Wayamba University of Sri Lanka, Makandura, 2005)