Richard Arum, Irenee R. Beattie, Merced, Karly Ford, editors
SAGE Publications, 2015
Buku Teks
Smucker, Orden C.
American Book Company, 1955
Buku Teks
Brookover
American Book Company, 1955
Buku Teks
Illinois, 1962
Buku Teks
edited by Robert R. Bell
Dorsey Press, 1962
Buku Teks