D`Andrea, Vaneeta-Marie
Open University Press, 2005
Buku Teks
Evans, Norman, 1923-
Routledge, 2001
Buku Teks
Hogan, Christine
Eruditions Publishing, 1999
Buku Teks
Meyers, Chet
Jossey-Bass Publishers , 1993
Buku Teks
Hogan, Christine
Eruditions, 1999
Buku Teks