Richards, David A.J.
Oxford University Press, 1986
Buku Teks
Cohen, Andrew Jason, author
Polity, 2014
Buku Teks
Welch, Joseph N., author
Houghton Miffiln, 1956
Buku Teks
Amery, L.S., author
Oxford University Press, 1953
Buku Teks
Corwin, Edward S., author
William Sloane, 1949
Buku Teks