Mathur, Hari Mohan
Sage Publications, 1986
Buku Teks
Rapley, John, author
Lynne Rienner, 2007
Buku Teks
Cammack, Paul Anthony, author
Leicester University Press, 1997
Buku Teks
Wiarda, Howard J., author
Thomson/Wadsworth, 2004
Buku Teks
Penguin Books, 1978
Buku Teks