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Buku Teks
Wessely, J.E., author
Chicago dsb. Pollett Publ. 1946
Buku Referensi
London: Tiger Books International, 1994,
Buku Referensi
Yapp, R.H, author
University Press, 1927
Buku Teks
Raya Jayawati Ratnawilis Amanah Notonegoro, author
2000
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