Selfe, Paul
PAN Books, 1983
Buku Teks
Harahap, Syaiful W, author
Pustaka Sinar Harapan, 2000
Buku Teks
edited by Peter Angleton
Taylor and Francis, 1996
Buku Teks
Willmore, Joe, author
American Society for Training & Development, 2006
eBooks
edited by Richard Haigh, Dai Harris
Routledge, 1994
Buku Teks