Swisher, Carl Brent, author
University of Chicago Press, 1946
Buku Teks
Schwartz, Bernard, author
Hill and Wang, 1963
Buku Teks
McLaughlin, Andrew C., author
Appleton Century Crofts, 1935
Buku Teks
Hocket,Homer Carey
Macmillan, 1939
Buku Teks
Wilson, Woodrow
Columbia University, [date of publication not identified]
Buku Teks