The World bank
World Bank
World Bank, 1981
 Buku Teks
MacKay, R.A.
The modern world
The Ryerson Press, 1935
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Perspectives on world
Routledge, 1992
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The World in figures
editorial information compiled by the Economist
The Economist Newspaper Limited, 1984
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World atlas
University of Technology Sydney
Lovell Johns , 1996
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