Thompson, Anthony
UNESCO, 1983
Buku Referensi
Lawal, Ibironke O.
Chandos Publishing, 2009
Buku Teks
edited by Allen Kent
Marcel Dekker, 1983
Buku Referensi
Reitz, Joan M.
Libraries Unlimited, 2004
Buku Referensi
Rubin, Richard E.
Neal-Schuman Publishers, Inc. , 1998
Buku Teks