Cook, I, and EV Lambert. “Sources of Variance and Reliability of Objectively Monitored Physical Activity in Rural and Urban Northern Sotho-Speaking Blacks”. South African Journal of Sports Medicine 20, no. 1 (March 5, 2008): 21–26. Accessed May 5, 2024. https://journals.assaf.org.za/index.php/sajsm/article/view/288.