List of sources:
Barnard, K.H. Personal names in South African conchology. Cape Town: Conchological Society of Southern Africa, 1965.
Cape of Good Hope. Report of the committee of the Albany Museum, 1898, 1906, 1907, 1909; and Albany Museum. Report, 1912, 1913.
Eastern Province Naturalists' Society. Minute Book, 12 January 1882 - 22 May 1885; Minute Book, 3 July 1885 - 4 March 1892; Ninth Annual Report... for the year 1890. (Africana Collection, Port Elizabeth Public Library.)
FamilySearch: John Farquhar. https://www.familysearch.org/tree/person/details/LWJ9-FN8
Grahamstown Journal, 24 April 1884, p. 3: "Eastern Province Naturalists' Society".
Herbert, D. & Kilburn, D. Field guide to the land snails and slugs of eastern South Africa. Pietermaritzburg: Natal Museum, 2004.
Kilburn, R. & Rippey, E. Sea shells of southern Africa. Johannesburg: Macmillan, 1982.
Port Elizabeth Museum. Report, 1888, 1889.