Titmuss, Richard M
Longmans Green and Co, 1950
Buku Teks
Sage Publications, 2002
Buku Teks
Carney, Terry
Oxford University Press Australia, 1991
Buku Teks
Stein, Theodore J.
Columbia University Press, 2001
Buku Teks
edited and introduced by Andrew Shonfield and Stella Shaw
Heinemann Educational Books, 1972
Buku Teks