Wang, James C.F.
Prentice-Hall, 1994
Buku Teks SO
Merriam, Charles E. (Charles Edward)
New York University Press, 1936
Buku Teks SO
Solomos, John
Routledge, 1995
Buku Teks SO
Gilpin, Robert
Cambridge University Press, 1981
Buku Teks SO
Aitkin, Donald Alexander
Australian National University Press, 1982
Buku Teks SO