Midgley, James, author
Sage Publications, 1997
Buku Teks
Friedlander, Walter A., author
Prentice Hall of India, 1982
Buku Teks
Gilbert, Neil, author
Prentice-Hall, 1986
Buku Teks
Australian council of social service, 0
Buku Teks
Schneider, Jo Anne, author
Columbia University Press, 2006
Buku Teks