edited by Cheryl Gamble
American Society for Training & Development, 2010
eBooks
Mulvaney, Robert J., author
Essex Pearson, 2014
Buku Teks
United Nations , 1987
Buku Teks
edited by James A. Gould
Merril Publishing, 1989
Buku Referensi
Fink, Arlene, author
Thousand Oaks : SAGE PUBLIKATION, 2003,
Buku Referensi