Oxford University Press, 1995
Buku Teks
Schulz, Ernest B
[publisher not identified], 1956
Buku Teks
Shi Biqiu
China Renmin University Press, 2015
eBooks
Arblaster, Anthony
Open University Press, 1987
Buku Teks
Pennock, J. Roland
Rinehart and Company, 1950
Buku Teks