List of sources:
Cape of Good Hope almanac and annual register, 1857.
FamilySearch: Henry Whitehead. https://www.familysearch.org/ark:/61903/3:1:33S7-9TM8-1GJ?view=index&personArk=/ark:/61903/1:1:KZ5D-H3X&action=view&cc=1921305&lang=en&groupId=M9G3-8F3
Gunn, M. & Codd, L.E. Botanical exploration of southern Africa. Cape Town: Balkema, 1981.
Harvey, W.H. & Sonder, O.W. Flora Capensis, being a systematic description of the plants of the Cape Colony, Caffraria, and Port Natal (Vol. 2). Ashford, Kent: Lovell Reeve, 1894 (originally published 1862).
Gutsche, T. The Bishop's lady. Cape Town: H. Timmins, 1970.