Frederick A, Praeger; George Allen and Unwin Ltd., 1964
Buku Teks
Gallagher, Matthew P.
Frederick A. Preager, 1963
Buku Teks
Carr, Edward Hallet
Macmillan, 1954
Buku Teks
Stephan, John J.
Stanford University Press, 1994
Buku Teks
Fischer, Louis
Princeton University Press, 1951
Buku Teks