Marais Ben J, Gupta Amita, Starke Jeffrey R, El Sony Asma
Department of Paediatrics and Child Health, Faculty of Health Sciences, Stellenbosch University, Tygerberg 7505, South Africa.
Lancet. 2010 Jun 12;375(9731):2057-9. doi: 10.1016/S0140-6736(10)60579-X. Epub 2010 May 18.