List of sources:
Charles Sirr Orpen. Geni. Retrieved from https://www.geni.com/people/Charles-Sirr-Orpen/6000000019077480675
on 2019-1-16.
Coetzer, A.C.M. Geskiedenis van die Nasionale Museum, 1877-1911. Navorsinge van die Nasionale Museum, 1989, Vol. 6(8), pp. 243-291.
Draper, D. Catalogue of the "Rupert Jones" collection of papers and manuscripts. Transactions of the Geological Society of South Africa, 1898, Vol. 4, pp. 77-86.
Friend of the Free State and Bloemfontein Gazette, 19 July 1877, p. 3 and 26 July 1877, p. 3 (reports on a public meeting to found a State Museum).
Grahamstown Journal, 29 December 1855, p. 2, Grahamstown Medico-Chirurgical Society.
Heese, J.A. South African genealogies. Pretoria and Stellenbosch, 1986-2005.
Hoffman, A.C. Interesting aspects about the early history of the National Museum in Bloemfontein. Southern African Museums Association Bulletin (SAMAB), 1958, Vol. 6, pp. 332-336.
Humphreys, A.J.B. The earliest reported shelter excavation in the interior of South Africa? South African Archaeological Bulletin, 1975, Vol. 30, p. 40.
National Automated Archival Information Retrieval System (NAAIRS). http://www.national.archives.gov.za/naairs.htm Documents relating to Orpen, Charles Sirr / Orpen, Charles S. / Orpen, Charles / Orpen, C.S.
National Museum. OFS Monthly Magazine, September 1879, Vol. 2, pp. 977-978.
South African bibliography to the year 1925. London: Mansell, 1979.
Stevenson, M. A forgotten Eastern Cape frontier artist: Richard John Newenham Orpen. Quarterly Bulletin of the South African Library, 1997, Vol. 51(4), pp. 161-164.
Stow, G.W. The native races of South Africa (pp. 63-64). Cape Town: Juta, 1905.