The encyclopedia of philosophy; volume 7 and 8
editor in chief, Paul Edwards
Macmilan , 1972
Buku Referensi
International encyclopedia of the social sciences : volume 7 & 8
edited by David L. Sills
Macmillan and The Free Press, 1968
Buku Referensi
Encyclopedia of knowledge : volume 7
Grolier Incorporated, 1991
Buku Referensi
The Encyclopedia Americana : volume 7
Grolier, 1994
Buku Referensi
The Encyclopedia Americana : volume 7
Americana Corporation, 1977
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