Weiher, Kenneth
Twayne, 1992
Buku Teks
Risjord, Norman K.
Prentice-Hall, 1985
Buku Teks SO
Alden, John Richard
American Book Company, 1960
Buku Teks SO
Williams, T. Harry
Alfred A. Knopf, 1963
Buku Teks SO
Beard, Charles A.
New Home Library, 1944
Buku Teks SO