Kristen, I, Fuhrmann, A, Thorpe, J, Röhl, U, Wilkes, H and Oberhänsli, H (2007) Hydrological changes in southern Africa over the last 200 kyr as recorded in lake sediments from the Tswaing impact crater. South African Journal of Geology, Special Issue, 110. 311-326. doi:10.2113/gssajg.110.2-3.311