List of sources:
Cape of Good Hope Government Gazette, 9 January 1885, pp. 41-45: List of licensed medical practitioners in the Cape Colony.
Cape Times, 8 July 1896, p. 5: Röntgen at the Rand.
FamilySearch. https://www.familysearch.org/ark:/61903/1:1:QR85-HDZM AND https://www.familysearch.org/ark:/61903/1:1:QPWW-DKQT AND https://www.familysearch.org/ark:/61903/1:1:6ZH5-S6G5
Medical, dental and pharmacy directory of South Africa, 1926/7.
Medical, dental and pharmacy register for the Transvaal, 1907. (National Archives, Pretoria, Vol. TKP301).
National Automated Archival Information
Retrieval System (NAAIRS). http://national.archives.gov.za/naairs.htm Documents relating to Dr William Robertson / Dr W. Robertson.
Plug, C. Almost forgotten, never told: The Griqualand West Medical Society (1882). Adler Museum Bulletin, April 1992, Vol. 18(1), pp. 2-8.
Plug, C. The introduction of röntgen rays and radiography into South Africa in 1896. Adler Museum Bulletin, March 2001, Vol. 27(1), pp. 4-10.
South African Medical Journal, Series 1, 1884, Vol. 1; Series 2, 1896, Vol. 4-5.
Staats-almanak der Zuid-Afrikaansche Republiek, 1898, pp. 86-93: Naamlijst van de geadmitteerde genees-, heel- en verloskundigen, tandheelkundigen, chemisten en drogisten.