Schawartz, Bernard, author
Oxford University Press, 1977
Buku Teks
Schwartz, Bernard, author
McGraw-Hill, 1971
Buku Teks
Rutland, Robert Allen
Collier-Macmillan Ltd., 1969
Buku Teks
D.C. Heath and Company, 1992
Buku Teks
Douglas, William O., author
Doubleday, 1961
Buku Teks