Beer, Credric de
Africa World, 1986
Buku Teks
Hofman, Michael, author
Oxford University Press, 2017
eBooks
Fordham, Paul
Penguin Books, 1972
Buku Teks
Spooner, F.P.
Fredereck A.Praeger Publisher, 1960
Buku Teks
Davidson, Basil, author
Time-Life International, 1967
Buku Teks