Porter, Charles O. (Charles Orlando), 1919-2006
Macmillan, 1961
Buku Teks SO
Arblaster, Anthony
Open University Press, 1987
Buku Teks
Oxford University Press, 1995
Buku Teks
Schulz, Ernest B
[publisher not identified], 1956
Buku Teks
Shi Biqiu
China Renmin University Press, 2015
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