Arblaster, Anthony, author
Open University Press, 1987
Buku Teks
Oxford University Press, 1995
Buku Teks
Schulz, Ernest B
[publisher not identified], 1956
Buku Teks
Shi Biqiu, author
China Renmin University Press, 2015
eBooks
David Marquand; Ronald L. Nettler., editor
Blackwell Publisher, 2000
Buku Teks SO