Ballantine, Joseph W., author
The Brooking Institution, 1952
Buku Teks
Rosati, Jerel A., 1953-, author
Wadsworth, 2007
Buku Teks
Rosati, Jerel A., 1953-, author
Thomson, 2004
Buku Teks
edited by Robert W. Tucker, Charles B. Keely, and Linda Wrigley
Westview Press, 1990
Buku Teks
Pratt, Julius W., author
Prentice-Hall, 1965
Buku Teks