• https://scholar.ufs.ac.za/items/dc3e18f4-3ec0-4017-b0b4-e0b11fadff66
• https://scholar.ufs.ac.za/items/ee000ea6-8a3c-4207-9a35-9b2193da67cf
• https://scholar.ufs.ac.za/items/fac17f26-6094-4e07-b0d2-a396a4dff5f0
• https://scholar.ufs.ac.za/items/fe788c11-2a33-4203-b71c-a409226e81b8
• https://scholar.ufs.ac.za/items/ff77de6b-a5ec-4e72-be30-c7109baddbd7