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P. A. Struck, 1941
Buku Referensi
Randall, David, author
Pluto Press, 2007
Buku Teks
The Hankes Foundation, 1992
Multimedia
Arthur, Paul, 1924-, author
Focus Strategic Communications, 2005
Buku Teks
Vloten, H. Van
Universitaire Pers Leiden, 1949
Buku Teks