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