Nicholson, Michael, author
Liverpool University Press , 1972
Buku Teks
edited by David N. Balaam and Michael J. Carey
Allanheld, Osmun, 1981
Buku Teks
Bettina E. Schmidt, Ingo W. Schroder, editor
Routlegde , 2001
Buku Teks
Ford Foundation , 1978
Buku Teks
Boulding, Kenneth E. (Kenneth Ewart), 1910-1993, author
Harper, 1963
Buku Teks