Foreign and Commonwealth Office
Her Majesty's Stationery Office, 1986
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Straits Times Press, 1971
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Clarendon Press, 1987
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Newspaper Enterprise Association, 1985
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Iwan Gunawan, Lena Sumargana, Nani Hendiarti, Guy Adamsyah
Directorate of technology for natural resources development, 1995
Buku Referensi