Não informado. (1950). Alex L. du Toit Memorial Lectures. Geological Society of South Africa.
Lua i Stíl Chicago (17ú heag.)Não informado. Alex L. Du Toit Memorial Lectures. Johannesburg, Africa do Sul: Geological Society of South Africa, 1950.
Lua MLA (8ú heag.)Não informado. Alex L. Du Toit Memorial Lectures. Geological Society of South Africa, 1950.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.