by Janice McLaughlin, Paul Rosen, David Skinner and Andrew Webster
Routledge, 1999
Buku Teks
Lembaga Penelitian Universitas Indonesia, 2007
Artikel Jurnal
Mahyuni, author
Universitas Mataram. FKIP, 2007
Artikel Jurnal
Carr, Patricia A.
American Society for Training & Development, 2006
eBooks
editor, Wiendu Nuryanti
Gadjah Mada University Press , 1996
Buku Referensi