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Journal Article The South African Journal of Science Get access The South African Journal of Science. Volume XVI., No. 5. (April–July, 1920.) African Affairs, Volume XX, Issue LXXVIII, January 1921, Page 159, https://doi.org/10.1093/oxfordjournals.afraf.a101747 Published: 01 January 1921
A Sat, study studied this question.