Zaidi, A.K.M.Awasthi, S.de Silva, H.J.2014-10-292014-10-292004British Medical Journal. 2004; 328(7443): pp.811-150959-8138 (Print)1756-1833 (Electronic)http://repository.kln.ac.lk/handle/123456789/1619Indexed in MEDLINENo Abstract AvailableReviewMedicine