Simons, Ronald L., author
Macmillan, 1985
Buku Teks
Seden, Janet, author
Open University Press, 2005
Buku Teks
Miley, Karla Krogsrud, 1942-, author
Pearson, 2014
Buku Teks
Walker, Hilary, author
Learning Matters Ltd., 2008
Buku Teks
Zastrow, Charles, author
Thomson Brooks/Cole, 2006
Buku Teks