List of sources:
FamilySearch: John Alexander Campbell. https://www.familysearch.org/ark:/61903/3:1:3Q9M-C91L-898P-R?view=index&personArk=/ark:/61903/1:1:6CT4-TDPX&action=view
Journal of the South African Chemical Institute, first decennial index, Volumes I to X, 1918-1927. Johannesburg: SACI, 1928.
South African Chemical Institute. Proceedings and list of members, 1921/2; 1933/4.