Crystallopollen angustifolium Steetz

Baumann, G. (2005). Photographic Guide to Wildflowers of Malawi Wildlife and Environmental Society of Malawi Pages 180 - 181. as Vernonia poskeana (Includes a picture).

Chapano, C. & Mugarisanwa, N.H. (2003). Plants of the Matobo District National Herbarium and Botanic Garden, Zimbabwe Page 37. as Vernonia steetziana and subsp. botswanica

Da Silva, M.C., Izidine, S. & Amude, A.B. (2004). A preliminary checklist of the vascular plants of Mozambique. Southern African Botanical Diversity Network Report No. 30 Sabonet, Pretoria Page 36. as Vernonia poskeana and V. steetziana

Heath, A. & Heath, R. (2009). Field Guide to the Plants of Northern Botswana including the Okavango Delta Kew Publishing Page 38. as subsp. botswanica (Includes a picture).

Kirby, G. (2013). Wild Flowers of Southeast Botswana Struik Nature, Cape Town South Africa Page 305. as subsp. botswanica (Includes a picture).

Mapaura, A. & Timberlake, J. (eds) (2004). A checklist of Zimbabwean vascular plants Southern African Botanical Diversity Network Report No. 33 Sabonet, Pretoria and Harare Page 29. also as Vernonia steetziana, V. erinacea and subsp. botswanica

Phiri, P.S.M. (2005). A Checklist of Zambian Vascular Plants Southern African Botanical Diversity Network Report No. 32 Page 35. as Vernonia poskeana subspp. poskeana & samfyana, V. steetziana

Pope, G.V. (1992). Compositae Flora Zambesiaca 6(1) Pages 147 - 150. also as V. steetziana and V. erinacea, subsp. botswanica and samfyana

Robinson, H. (1999). Revisions in paleotropical Vernonieae (Asteraceae) Proc. Biol. Soc. Washington 112(1) Page 233. as Polydora poskeana and P. steetziana

Robinson, H., Skvarla, J.J. & Funk, V.A. (2016). Vernoneae (Asteraceae) of Southern Africa: A generic disposition of the species and a study of their pollen. Phytokeys 60 Pages 105 - 107. as Polydora angustifolia, P. poskeana & P. steetziana

Setshogo, M.P. (2005). Preliminary checklist of the plants of Botswana. Sabonet Report no. 37. Sabonet, Pretoria and Gaborone Page 39. as Vernonia steetziana and subsp. botswanica

Shone, D.K. & Drummond, R.B. (1965). Poisonous Plants of Rhodesia Ministry of Agriculture, Rhodesia Page 59. as Vernonia poskeana

Siebert, S. & Mössmer, M. (Editors) (2002). SABONET Southern Mozambique Expedition 2001; Provisional Plant Checklist of the Maputo Elephant Reserve (MER) and Licuati Forest Reserve (LFR) SABONET News 7(1) Page 24. as Vernonia poskeana

Timberlake, J.R. & Childes, S.L. (2004). Biodiversity of the Four Corners Area: Technical Reviews Volume Two (Chapter 5-15) Appendix 5-1: Plant Checklist Occasional Publications in Biodiversity 15 Page 201. as Vernonia poskeana

Wild, H. (1978). New and interesting Vernonia species from the Flora Zambesiaca area Kirkia 11(1) Pages 2 - 3. as Vernonia poskeana