D`Andrea, Vaneeta-Marie, author
Open University Press, 2005
Buku Teks
Biggs, John B., author
McGraw-Hill, 2011
Buku Teks
Walker, Melanie, author
Open University Press, 2004
Buku Teks
Evans, Norman, 1923-, author
Routledge, 2001
Buku Teks
edited by Heather Fry, Steve Ketteridge and Stephanie Marshall
Routledge, 2009
Buku Referensi