Smith, C. C. D., L. G. Underhill, and M. Brooks. “Bird Distribution Dynamics 13 - the Grebes of South African, Lesotho and Swaziland”. Biodiversity Observations, vol. 8, Apr. 2017, pp. 21: 1 - 14, https://journals.uct.ac.za/index.php/BO/article/view/419.