Webster, Frank
Routledge, 1995
Buku Teks SO
Martin, William J.
Brookfield, Vt., USA : Gower,, 1995.
Buku Teks SO
Terranova, Tiziana
Pluto Press, 2005
Buku Teks SO
Castells, Manuel
Blackwell, 1998
Buku Teks SO
Castells, Manuel
Blackwell, 1997
Buku Teks SO