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 3 and 4
editor, Paul Edwards
MacMilan, 1972
 Buku Referensi
The Encyclopedia of philosophy: volumes 5 and 6
editor in chief Paul Edward
MacMilan, 1972
 Buku Referensi
The encyclopedia of philosophy; volume 7 and 8
editor in chief, Paul Edwards
Macmilan , 1972
 Buku Referensi