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Buku Referensi
edited by Frank A. Oski, James A. Stockman
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Foreign and Commonwealth Office
Her Majesty's Stationery Office, 1986
Buku Referensi
The Straits Times Press, 1971
Buku Teks
edited by Gillenwater, Jay Y., editor; Howards, Stuart S., editor
Mosby Year Book, 1990
Buku Referensi