Thomlinson, Ralph, author
Dickenson Publishing, 1975
Buku Teks
Kpedekpo, G.M.K.
Heinemann, 1982
Buku Teks
Wunsch, Guillaume J., author
Plenum Press, 1978
Buku Teks
The Population Reference Bureau, Inc., 1976
Buku Teks
Thomlinson, Ralph
California State University, 1976
Buku Teks