Wagner, Susan
Praeger Publishers, 1971
Buku Teks
Lowenthal, Max
Greenwood Press, 1971
Buku Teks
Lowenthal, Max
William Sloane Associates, Inc., 1950
Buku Teks
edited by Philip A. Shaver
Warren, Gorham and Lamont, 1969
Buku Teks
Warren, Gorham & Lamont, Inc. , 1971
Buku Teks