Hazlewood, Arthur, author
Pergamon Press, 1982
Buku Teks
Bagachwa, M.S.D., author
International Development Research Center, 1991
Buku Teks
Webb, Walter Prescott, author
Grosset & Dunlap, 1931
Buku Teks
Murnane, Gerald
Penguin Books, 1982
Koleksi Publik
Yeager, Rodger, author
Westview Press, 1989
Buku Teks