Wolf, Martin L., author
Philosophical Library, 1951
Buku Referensi
Willetts, William Y., author
Penguin Books , 1958
Buku Teks
Burling, Judith, author
Thames and Hudson, 1953
Buku Teks
Sayre, Henry M, author
Prentice-Hall, 1997
Buku Teks
Phaidon, 1994
Buku Teks