List of sources:
British Association for the Advancement of Science. Report of the seventy-fifth meeting... South Africa, 1905, list of members.
Cape of Good Hope. Civil service list, 1901, 1902.
Cape of Good Hope. Report of the Government Electrical Engineer, 1899.
Draper, J.R. The engineer's contribution: A history of the South African Institution of Mechanical Engineers, 1892-1967 (p. 245). Johannesburg: SAIME, 1967.
FamilySearch: George Muirhead Clark. https://www.familysearch.org/search/record/results?q.anyDate.from=1869&q.givenName=George Muirhead &q.surname=Clark
General directory of South Africa (Cape Town), 1903.
George Muirhead Clark. In Grace's Guide to British Industrial History. http://www.gracesguide.co.uk/George_Muirhead_Clark
National Automated Archival Information Retrieval System (NAAIRS). http://www.national.archives.gov.za/naairs.htm Documents relating to Clark, G.M.
Royal Society of London. Catalogue of scientific papers [1800-1900]. London: Royal Society, 1867-1925.
Royal Society of South Africa. Transactions, 1908-1910, Vol. 1 and 1917, Vol. 6: Lists of members.
South African Association for the Advancement of Science. Report, 1918, list of members.
South African bibliography to the year 1925. London: Mansell, 1979.
South African Geographical Journal, 1917, Vol. 1(1), list of members.
South African Philosophical Society. Transactions, 1900-1907, Vol. 11, 16 and 17: Lists of members.