Lipton, Michael, author
Yayasan Ilmu-Ilmu Sosial, 1980
Buku Teks
Forsyth, David J.C., author
H.M. Stationery Off., 1979
Buku Teks
Okolie, Charles Chukwuma, author
Frederick A. Praeger, 1975
Buku Teks
Mountjoy, Alan B., author
Hutchinson University Library, 1963
Buku Teks
Mountjoy, Alan B., author
Hutchinson University Library, 1971
Buku Teks