Numelin, Ragnar
Oxford University Press, 1950
Buku Teks
Pratiwi A. Kinanthi, author
Policy Analysis and Development Agency, 2018
Artikel Jurnal
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2017
UI - Tugas Akhir
Spero, Joan Edelman, author
Wadsworth, 2010
Buku Teks
Maps Com, 2007
Buku Referensi