Dorfman, Robert, author
The University of California Press 1, 1951
Buku Teks
Marris, Robin, author
Free Press of Glencoe, 1964
Buku Teks
Williamson, Oliver E., author
Markham, 1967
Buku Teks
Triffin, Robert, author
Harvard University Press, 1941
Buku Teks
Broster, E.J., author
Longman, 1972
Buku Teks