Ritchie, Donald A., author
Macmillan, 1985
Buku Teks
Myers, Gustavus, author
Random House, 1943
Buku Teks
Myers, Margaret G., author
Columbia University Press , 1970
Buku Teks
Kemmerer, Donald L., author
Littlefield, Adams, 1956
Buku Teks
Williams, T. Harry, author
Alfred A. Knopf, 1963
Buku Teks