List of sources:
Agricultural Journal (Union of South Africa), 1913, Vol. 6, article by Von Wielligh.
Cape of Good Hope. Report of the Surveyor-General, 1880.
Dictionary of South African biography, Vol. 1, 1968.
Journal of the Institute of Land Surveyors of the Transvaal, 1905, Vol. 1(1), pp. 24-27, and 1909, Vol. 1(8), pp. 338-341: Lists of members.
Liebenberg, E.C. Die topografiese kartering van Suid-Afrika, 1879-1972; 'n histories-geografiese ontleding. MA-verhandeling in Geografie, Universiteit van Suid-Afrika, 1973.
National Archives Repository (TAB). Source SS, Vol. 837, Ref. R3693/83: G.R. van Wielligh has been admitted to practice in the South African Republic as a sworn land surveyor... (1883).
South African bibliography to the year 1925. London: Mansell, 1979 (Vol. 1-4) and Cape Town: SA Library, 19991 (Vol. 5).
Standard encyclopaedia of southern Africa (SESA). Cape Town: NASOU, 1970-1976.
Transvaal Colony. Civil service list, 1906, pp. 147-148, Government land surveyors.
University of the Cape of Good Hope. Calendar, 1884/5.
Weather Bureau. Bibliography of regional meteorological literature. Vol. 1. Southern Africa, 1486-1948 (compiled by R.J. Venter). Pretoria: Weather Bureau, 1949.