Jerrard, Jane, author
American Management Association, 2009
eBooks
Yates, Rochelle, author
Library Professional Publications, 1986
Buku Teks
Bien, Thomas, author
Wisdom Publications, 2006
Buku Teks
McLeod, John, author
McGraw-hill Open University press, 2012
Buku Teks
Loughary, John W., author
McGraw-Hill, 1979
Buku Teks