List of sources:
African court calendar, 1806, 1810-1814. Reprinted by the South African Library, Cape Town, 1982.
Cape of Good Hope. Report of the commissioners appointed for the purpose of determining the unit of land measure within the Colony... (Parliamentary Report G1-'59). Cape Town: Saul Solomon, 1859.
Dictionary of South African biography, Vol. 2, 1972.
FamilySearch: Johannes Willem Wernich. https://ancestors.familysearch.org/en/LH64-2CW/johannes-willem-wernich-1764-1814
Fisher, R. Land surveyors and land tenure at the Cape, 1657-1812. In C.G.C. Martin & K.J. Friedlaender (eds), History of surveying and land tenure in South Africa. Collected papers, Vol. 1. University of Cape Town, Department of Surveying, 1984.
Hoge, J. Personalia of the Germans at the Cape, 1652-1806. Archives Yearbook for South African History. Cape Town: Government Printer, 1946, pp. 1-485.
Koeman, C. Nieuwe bijdragen tot de kennis van Zuid-Afrika's historische kartografie. Tijdschrift van het Koningklijk Nederlands Aardrijkskundig Genootschap, 1952, Vol. 69, pp. 73-5.
National Automated Archival Information Retrieval System (NAAIRS). http://national.archives.gov.za/naairs.htm Documents relating to Wernich, Jan Willem / Wernich, J.W.