List of sources:
Addresses and papers read at the joint meeting of the British and South African Associations for the Advancement of Science held in South Africa, 1905 (Vol. 1). Johannesburg: SAAAS.
British Association for the Advancement of Science. Report of the seventy-fifth meeting... South Africa, 1905.
Chemical, Metallurgical and Mining Society of South Africa. Proceedings, 1902-1903, Vol. 3, list of members; Journal, 1904/5, Vol. 5, Members; 1909-1910, Vol. 10, papers by Croghan.
Google scholar. http://scholar.google.co.za Publications by E.H. Croghan.
Hall, A.L. A bibliography of South African geology to the end of 1920. Pretoria: Geological Survey, Memoir No. 18, 1922.
Identity Number, at http://www.identitynumber.org/marriage-lookup-surname-results1.php?surname=LAWRIE
as on 2016-5-11.
National Automated Archival Information Retrieval System (NAAIRS). http://www.national.archives.gov.za/naairs.htm Documents relating to Edward Henry Croghan / EH Croghan.
Ritchie, W. The history of the South African College, 1829-1918. Cape Town: T. Maskew Miller, 1918.
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Wills, W.H. The Anglo-African who's who and biographical sketch book. London: Upcott, 1910.