The New York times 2004 almanac
edited by John W. Wrigth
Penguin Group, 2003
 Buku Referensi
The World almanac and book of facts 1983
Newspaper Enterprise Association, 1982
 Buku Referensi
The World almanac and book of facts 1988
Newspaper Enterprise Association, 1987
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The World almanac and book of facts 1986
Newspaper Enterprise Association, 1985
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Information please almanac, atlas and yearbook 1961
planned and supervised by Dan Golenpaul Associates
McGraw-Hill, 1960
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