Jacobsen, Kathyn
Jones & Bartlett Learning, 2012
Buku Teks
French, Sally
Butterworth-Heinemann, 2001
Buku Referensi
Sophie Laws, Caroline Harper, Nicola JOnes, Rachel Marcus
Sage, 2013
Buku Teks
Denscombe, Martyn
Open University Press, 2012
Buku Teks
Ewles, Linda
Scutari Press, 1995
Buku Referensi