Asian Development Bank, 1986
Buku Teks
Andrews, Gladys
0, 1960
Buku Teks
Education Research Institute Seoul National University, 2005
Majalah, Jurnal, Buletin
edited by Susan Higgins, Meta Brett
Longman, 1984
Buku Referensi
Sandra Fikawati
Career Development Center Universitas Indonesia, 2011
UI - Makalah dan Kertas Kerja