Sembiring, Riswanto, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2010
UI - Tesis (Open)
Prager, Jonas
Random House , 1971
Buku Teks
editor, Frank N. Magill
Salem Press, 1991
Buku Referensi
Langer, Paul F.
Hoover Institution Press, 1972
Buku Teks
Dulles, John Foster
Macmillan Company, 1950
Buku Teks