Edwards, Sebastian
MIT Press , 1989
Buku Teks
Hilling, David, author
Routledge, 1996
Buku Teks
King, Felicity Savage, author
Oxford University Press, 1995
Buku Teks
Ross, Harold, author
United Nations Research Institute for Social Development, 1972
Buku Teks
Zenoff, David B.
Prentice-Hall, 1969
Buku Teks