Davidson, Basil, author
Time-Life International, 1967
Buku Teks
Jakarta : The Ambassador of The Republic of Zimbabwe, 2007,
Majalah, Jurnal, Buletin
Katzner, Kenneth, author
Routledge, 1995
Buku Referensi
Peter Lang International Academic Publishin Group, 2010
Majalah, Jurnal, Buletin
edited by Diane Brentari
Cambridge University Press, 2010
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