Wickramasinghe, R.K.; Abeygunawardena, S.I.; Widanapathirana, S.; Jayarathne, D.L.(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2002)
Karunathilake, K.; Karunaratne, H.W.; Sisira Kumara, G.W.D.N.; Dissanayeke, D.M.U.(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2002)