Lewis, William Arthur, author
University of Ghana by the Ghana Pub, 1971
Buku Teks
McNulty, James E., author
University of Pennsylvania Press, 1964
Buku Teks
Australian Government Publishing Service , 1979
Buku Teks
Epstein, T. Scarlett, author
Australian National University Press, 1968
Buku Teks
Henry, Andrew F., author
Macmillan, 1964
Buku Teks