Laurie, Ian C.
Chichester: John Wiley & Sons, 1979
Buku Teks
by Catherine Bauer [and others]; edited by Coleman Woodbury
The University of Chicago Press, 1953
Buku Teks
Amin, Ash
Polity Press, 2010
Buku Teks
Stevenson, Deborah
Open University Press, 2003
Buku Teks
Forman, Richard T. T.
Cambridge University Press, 2014
Buku Teks