Joy Hakim, author
Oxford University Press, 2003
Buku Teks
Trofimenko, Genrikh
Progress Publishers, 1986
Buku Teks
edited by Kathleen E. Hug
Office of International Infrmation Programs US Department of State, [Date of publication not identified]
Buku Teks
Baker, Ross K., author
Free Press, 1980
Buku Teks
Ganziro, Taranza T., author
Emerald, 2016
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