List of sources:
Cape of Good Hope. Report of the Principal of the Agricultural School at Elsenburg, 1909.
Crawford, David Chalmers. University of Aberdeen
Roll of Honour. https://www.abdn.ac.uk/library/roll-of-honour/1095/
FamilySearch: David Chalmers Crawford. https://www.familysearch.org/ark:/61903/1:1:6CNY-8KW2 and https://www.familysearch.org/ark:/61903/1:1:6ZC9-QQB3
Google scholar. http://scholar.google.co.za/ Publications by D.C. Crawford.
National Automated Archival Information Retrieval System (NAAIRS), at http://www.national.archives.gov.za/naairs.htm Documents relating to David Chalmers Crawford.
Sim, J.T.R. Agronomy investigations in the winter rainfall region, 1892-1953. Department of Agriculture, Science Bulletin No. 373, 1958 (and Stellenbosch-Elsenburg Science Series No. 53).
South African Association for the Advancement of Science. Report, 1914, paper by A.I. Perold and D.C. Crawford; 1918, list of members.
Union of South Africa. Public Service List, 1914. Pretoria: Government Printer, 1914.