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Norwalk Appletton century crofts , 1985
Buku Teks
Hanover Pub.,, 1981
Buku Referensi
Dong-Kyun Park
ESCAP, 2017
Artikel Jurnal
Fell-Carlson, Deborah L.
Thomson/Delmar Learning, 2008
Buku Teks
Susiana Nugraha
Universitas Indonesia, 2017
Artikel Jurnal