K. Monyeki, M. Monyeki, S. Brits, H. Kemper, and P. Makgae, “Development and Tracking of Body Mass Index from Preschool Age into Adolescence in Rural South African Children: Ellisras Longitudinal Growth and Health Study”, J Health Popul Nutr, vol. 26, no. 4, pp. 405–417, Jan. 2009.