edited by B.S. Hoyle
John Wiley & Sons, 1978
Buku Teks
Lewis, William Arthur, author
University of Ghana by the Ghana Pub, 1971
Buku Teks
Bunn, Isabella D., author
Hart Publishing, 2012
Buku Teks
Carey-Jones, N.S.
Croom Helm, 1974
Buku Teks
Evans, Luther H.
Oceana Publications, Inc., 1966
Buku Teks