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Ewell, Peter T.
Ithaca, N.Y. Department of Agricultural Economics Cornell University 1984,
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The Ary Suta Center, 2018
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Mohammad Hasroel Thayib
The Ary Suta Center, 2018
Artikel Jurnal
Nainggolan, Kaman
Pustaka Sinar Harapan, 2005
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