Rose, Janet, author
Open University Press, 2012
Buku Teks
[publisher not identified], 1968
Buku Teks
Smidt, Sandra, author
Routledge, 2007
Buku Teks
Hubbard, L. Ron, 1911-1986, author
Bridge Publications, Inc., 2012
Buku Referensi
Sroufe, L. Alan, author
Cambridge University Press, 1996
Buku Teks