Drucker, Peter F. (Peter Ferdinand), 1909-2005, author
The New American Library, 1964
Buku Teks
Hart, H.L.A., author
Oxford University Press, 1979
Buku Teks
Hart, H.L.A., author
Clarendon Press, 1979
Buku Teks
Hart, H.L.A., author
United Kingdom Oxford University Press, 2012
Buku Teks
Ryle, Gilbert
Hutchinson's University Library, 1950
Buku Teks