Dasmann, Raymond F. (Raymond Fredric), author
John Wiley & Sons, 1972
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Simanjuntak, Wasinton, author
Universitas Lampung. Faculty of Mathematics and Natural Science, 2014
Artikel Jurnal
Panjaitan, Pohan, author
Universitas HKBP Nonmensen, 2016
Artikel Jurnal
edited by Serge A. Wich, Andrew J. Marshall
Oxford University Press, 2016
eBooks
edited by Joan Davidson and Richard Lloyd
John Wiley & Sons, 1979
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