Kagan, Shelly, author
Westview Press, 1997
Buku Teks
Cambridge University Press, 2015
Buku Teks
Albert, Ethel M., author
American Book Company, 1953
Buku Teks
Pojman, Louis P., author
Wadsworth and Cengage Learning, 2012
Buku Teks
Thiroux, Jacques P. author
Pearson, 2015
Buku Teks