Kunkel, Vicki, author
American Management Association, 2009
eBooks
Cossman, Joe
Prenhallindo , 1997
Buku Teks
Sudarminto
Teori dan Praktek, 2002
Buku Teks
Hendro, author
Andi, 2005
Buku Teks
Hansen, Mark Victor, author
Gramedia Pustaka Utama, 2006
Buku Teks