Dyer, Justin Buckley, author
Cambridge University Press, 2013
eBooks
Burnheim, John
University of California Press, 1985
Buku Teks
Burns, Danny, 1964-, author
Macmillan, 1994
Buku Teks
McKenna, George, author
McGraw-Hill, 1998
Buku Teks
Skidmore, Thomas E., author
Oxford University press, 2007
Buku Teks