1. Reid, C., in Plants of Southern Africa: Names and Distribution, ed. T. H. Arnold and B. C. de Wett. National Botanical Institute, Pretoria, 1993, p. 133.
2. Turton, L. M. and Kalake, E., A List of the Flowering Plants of Botswana in the Herbaria at the National Museum, Sebele and University of Botswana, The Botswana Society and The National Museum, Monuments and Art Gallery, Gaborone, 1994, p. 46.
3. Isofuranonaphthoquinones and phenolic and knipholone derivatives from the roots of Bulbine capitata
4. An anthrone, an anthraquinone and two oxanthrones from Kniphofia foliosa