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