Sweeney, Simon, author
Cambridge university press, 2010
Buku Teks
Bianki, V., author
Foreign Languages Publishing, [date of publication not identified]
Buku Teks
Wallwork, Adrian, author
Springer, 2010
Buku Teks
Emmerson, Paul, author
Cambridge University Press, 2005
Buku Teks
Cellich, Claude, author
Business Expert Press, 2012
Buku Teks