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Rand McNally College, 1969
Buku Teks
edited by Shepherd Laughlin
The Institute of International Education, 2008
Buku Teks
edited by Alma Harris and Janet H. Chrispeels
Routledge, 2006
Buku Teks
London : Hamish Hamilton Ltd
Majalah, Jurnal, Buletin
Artikel Jurnal