List of sources:
Geological Society of South Africa. Transactions, 1895-1906, Vol. 1-10: Lists of members and office bearers.
Hall, A.L. Bibliography of South African geology to the end of 1920. Pretoria: Geological Survey, Memoir No. 18, 1922.
National Automated Archival Information Retrieval System (NAAIRS). http://www.national.archives.gov.za/naairs.htm Documents relating to Chalmers, John Alexander/Chalmers, J.A.
South African Association for the Advancement of Science. Report, 1905/6, list of members.
South African bibliography to the year 1925. London: Mansell, 1979.
South African Association of Engineers and Architects. Proceedings, 1894, 1897-8, Vol. 1, 4: Lists of members.