Nanayakkara, K.G.M.; Wijetunge, W.A.D.S.(Department of Business Management, Faculty of Business Studies and Finance, Wayamba University of Sri Lanka. Kuliyapitiya, 2010)
Perera, H.S.R.; Udugama, J.M.M.; Jayasinghe-Mudalige, U.K.(Faculty of Agriculture and Plantation Management,Wayamba University of Sri Lanka, Makandura, 2013)