Former minister of labour and a moderate member of the National Party, Marais Viljoen, was inaugurated as South Africa's fifth state president after he had been elected on 4 June 1979. Viljoen replaced B.J Vorster who had resigned on that date. Before being elected to the position permanently, he served as acting state president for two months from August to October 1978. He served in the position until 3 September 1984 when was replaced by P.W. Botha.
Wallis, F. (2000). Nuusdagboek: feite en fratse oor 1000 jaar, Kaapstad: Human & Rousseau).