Artikel Jurnal
edited by Elsa Ramsden
W.B. Saunders, 1999
Buku Teks SO
Mahar Mardjono
Dian Rakyat, 1978
Buku Teks SO
Stephen L. Hauser, S. Andrew Josephson, editors
McGraw-Hill Education, 2017
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Taylor, Shelley E.
McGraw-Hill, 1995
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