Societa editrice il Muline, 1976
Buku Teks
Graham, Gordon
Routledge , 1997
Buku Teks
edited by Berys Gaut, Dominic Mclver Lopes
Routledge, 2005
Buku Teks
Santayana, George, author
Collier Books, 1961
Buku Teks
Sim, Stuart
Harvester Wheatsheaf, 1992
Buku Teks