Rapport, Nigel, author
Routledge, 2000
Buku Teks
Murphy, Robert F., author
Prentice-Hall, 1986
Buku Teks
Hammond, Peter, author
Macmillan, 1978
Buku Teks
Miller, Barbara D., author
Pearson Education, 2005
Buku Teks
Nanda, Serena, author
Wadsworth, 2002
Buku Teks