The Encyclopedia Americana : volume 20
Americana Corporation, 1964
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Collier's encyclopedia : volume 20
Macmillan Educational Company, 1990
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Encyclopedia of knowledge : volume 20
Grolier Incorporated, 1991
Buku Referensi
The Encyclopedia Americana : volume 20
Grolier, 1994
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Grolier family encyclopedia : volume 20
Grolier Incorporated, 1995
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