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
by Arthur I. Gates [and others]
Macmillan, 1962
Buku Teks