Retief, F. P.; Cilliers, L. (January 1998). "The epidemic of Athens, 430-426 BC". South African Medical Journal = Suid-Afrikaanse Tydskrif vir Geneeskunde. 88 (1): 50–53. ISSN0256-9574. PMID9539938.
Retief, F. P.; Cilliers, L. (January 1998). "The epidemic of Athens, 430-426 BC". South African Medical Journal = Suid-Afrikaanse Tydskrif vir Geneeskunde. 88 (1): 50–53. ISSN0256-9574. PMID9539938.