The encyclopedia of philosophy volume 7 and 8
Paul Edwards, editor in chief
Macmilan , 1972
 Buku Referensi
The encyclopedia of philosophy
editor, Donald M. Borchert
Macmilan, 1996
 Buku Referensi
Concise Routledge encyclopedia of philosophy
Routledge, 2000
 Buku Referensi
The encyclopedia of philosophy: volumes 1 and 2
editor, Paul Edwards
MacMilan, 1972
 Buku Referensi
The Encyclopedia of philosophy: volumes 3 and 4
editor, Paul Edwards
MacMilan, 1972
 Buku Referensi