Lowenthal, Max
Greenwood Press, 1971
Buku Teks
Lowenthal, Max
William Sloane Associates, Inc., 1950
Buku Teks
Tiffany, Lawrence P.
Little, Brown, 1967
Buku Teks
Way, H. Frank
McGraw-Hill, 1964
Buku Teks
edited by Burke Marshall
National Public Radio, 1982
Buku Teks