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, 1896, p. 226.
Cape of Good Hope. Report of the Meteorological Commission, 1900-1906.
Cape Society of Civil Engineers. Minutes of Proceedings, 1903-1907, Vol. 1-5.
Dictionary of South African biography, Vol. 5, 1987.
General directory and guide book to the Cape of Good Hope and its dependencies..., 1886 (p. 114).
Men of the times: Old colonists of the Cape Colony and Orange River Colony. Johannesburg: Transvaal Publishing Company, 1906.
National Archives Repository (TAB), Source MHG, Vol. 0, Ref. 94948: death notice, Robert Henry Hammersley-Heenan.
National Automated Archival Information Retrieval System (NAAIRS). http://www.national.archives.gov.za/naairs.htm Documents relating to Hammersley-Heenan, Robert / Hammersley-Heenan, R.H. / Heenan, R.H.H.
South African Association for the Advancement of Science. Report, 1903, 1905/6: Lists of members.
South African bibliography to the year 1925. London: Mansell, 1979.
South African Philosophical Society. Transactions, 1883-1906, Vol. 3, 4, 6-11, 16: Lists of members.
South African Society of Civil Engineers. Minutes of Proceedings, 1913, Vol. 11, Members.