Powell, Colin L., author
Angkasa, 2001
Buku Teks
Kriplen, Nancy, author
American Management Association, 2008
eBooks
Yates, Brock
Empire Books, 1983
Buku Teks
Chen, Xiangmei, author
Tianxia Wenhua Chuban Gongsi, 1995
Buku Teks
Shelp, Ronald Kent, author
John Wiley & Sons, 2009
Buku Teks