Pantry, Sheila
Facet Publishing, 2003
Buku Teks
Rogers, Jenny
McGraw-Hill, 2011
Buku Teks
Scott, Gini Graham
American Management Association, 2009
eBooks
Brause, Rita S.
RoutledgeFalmer , 2000
Buku Teks
Pinto, Jeffrey K.
Van Nostrand Reinhold, 1995
Buku Teks