Allen, Carleton Kemp, Sir
Stevens & Sons Limited, 1958
Buku Teks
Schulz, Ernest B
[publisher not identified], 1956
Buku Teks
Arblaster, Anthony
Open University Press, 1987
Buku Teks
Allen, Carleton Kemp, Sir
Stevens & Sons Limited, 1953
Buku Teks
Allen, Carleton Kemp, Sir
The Clarendon Press, 1964
Buku Teks