United Nations , 1990
Buku Teks
Hofman, Michael, author
Oxford University Press, 2017
eBooks
Williams, Robert, author
Gower, 1991
Buku Teks
edited by M. Fortes and E.E. Evans-Pritchard
Oxford University Press, 1950
Buku Teks
Kimble, George H.T.
The Twentieth Century Fund, 1960
Buku Teks