Christian, James L.
Wadsworth and Cengage Learning, 2012
Buku Teks
Eldridge, Richard
Cambridge, 2003
Buku Teks
Hauser, Arnold
Routledge & Kegan Paul, 1959
Buku Teks
Read, Herbert
World Publishing Company, 1962
Buku Teks
edited by Matthew Kieran
Blackwell, 2006
Buku Teks