Farmer, David Hugh, author
Oxford University Press, 1992
Buku Referensi
Blackburn, Simon, author
Buku Referensi
edited by Colin Howlett
Oxford University Press, 1996
Buku Referensi
edited by P. S. Falla
Clarendon Press, 1990
Buku Referensi
Oxford University Press, New York
Buku Referensi