D`Andrea, Vaneeta-Marie
Open University Press, 2005
Buku Teks
Institute for Scientific co-coperation, [date of publication not identified]
Majalah, Jurnal, Buletin
Barnett, Ronald
Open University Press, 1994
Buku Teks
edited by John C. Smart
Springer, 2011
Buku Teks
Norton, Lin S.
Routledge, 2009
Buku Teks