Jenkin, James, author
Lonely Planet Publications, 2006
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Katzner, Kenneth, author
John Wiley & Sons, 1994
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Preobrazhensky, A. G., author
Columbia University Press, 1951
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edited by Colin Howlett
Oxford University Press, 1996
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edited by P. S. Falla
Clarendon Press, 1990
Buku Referensi