List of sources:
Cape of Good Hope Government Gazette, 16 September 1862, "List of the medical practitioners in the Cape Colony...".
Burrows, E.H. A history of medicine in South Africa. Cape Town: Balkema, 1958.
Dictionary of South African biography, Vol. 3, 1977.
FamilySearch: William Gill. https://www.familysearch.org/ark:/61903/3:1:3Q9M-CSQF-XS99-P?view=index&personArk=/ark:/61903/1:1:QGLF-GL2N&action=view
Grahamstown Journal, 15 March 1856, p. 2, "Literary, Scientific and Medical Society".
Grisbrook, [C.H.] Notes on South African geology. South African Quarterly Journal, 1830, No. 4, pp. 446-447.
Gunn, M. & Codd, L.E. Botanical exploration of southern Africa. Cape Town: Balkema, 1981.
Laidler, P.W. and Gelfand, M. South Africa: Its medical history, 1652-1898. Cape Town: Struik, 1971.
National Automated Archival Information Retrieval System (NAAIRS). http://www.national.archives.gov.za/naairs.htm Documents relating to William Gill / W. Gill / Dr Gill.