Parson, Keneth H.
The University of Wisconsin Press, 1956
Buku Teks
Whittemore, Claire
Oxfam Public Affairs Unit, 1981
Buku Teks
Hooker, M. B., author
Oxford University Press, 1976
Buku Teks
Neale, Walter C., author
Yale University Press, 1962
Buku Teks
Hooker, M. B., author
Oxford University Press , 1972
Buku Teks