Elsevier, 2014
eBooks
Farid. Fara Mademah Ahmad
Edinburgh University Press, 2012
Buku Teks
edited by Chris Hale, Carolyn Boyle, Jo Moore
Globe Business, 2010
Buku Teks
Holt, David H.
Prentice-Hall, 1992
Buku Teks
Cooke, Darryl J.
Sweet & Maxwell, 2011
Buku Teks