The history of exports from South Africa involves a single major exporter: the Cape Provincial Authority (CPA) which sent African clawed frogs all over the world. The CPA kept records, and these were summarised in a study which was published in April 2016 (but cited here as unpublished data):

Van Sittert, L. & Measey, G.J. (2016) Historical perspectives on global exports and research of Africa...