List of sources:
Blue Book for the Colony of Natal, 1896, p. H144; 1898, p. H75.
Natal Agricultural Journal, 1898-1906, Vol. 1, 6, 7 and 9.
Natal civil service list, 1906.
Natal who's who, 1906.
National Automated Archival Information Retrieval System (NAAIRS). http://www.national.archives.gov.za/naairs.htm Documents relating to Challis, Edward Osmond/Challis, E.O.
National Union Catalogue, pre-1956 imprints. London: Mansell, 1968-1980.
Union of South Africa. Public service list, 1914.