O`brien, Kevin J
Cambridge University Press, , 2006
Buku Teks
edited by David S.G. Goodman
Routledge, 1997
Buku Teks
Colin Mackerras, Donald H.McMillen, Andrew Wastson
Routledge, 2001
Buku Teks
by Franz Michael, Carl Linden, Jan Pryblyla, Jurgen Domes
Westview Press, 1990
Buku Referensi
Enrich Professional Pub., 2012
Buku Teks