Tan, Kevin.
Butterworth Asia, 1997
Buku Teks
Olga Aikin
IPM, 1994
Buku Teks
Clarke, Linda, author
Institute of Personnel and Development, 1993
Buku Teks
Arif Wahyunadi, author
Unicef Indonesia, 2004
Buku Teks
edited by Gwemmeth Roberts, Kelsey Hegarty, Gene Feder
Elsevier, Cruchill Livingstone, 2006
Buku Teks