Cohen, Nathan Edward
National Ass. of Workker, 1964
Buku Teks
Healy, Karen
Palgrave Macmillan, 2005
Buku Teks
Aspinwall-Roberts, Elaine
McGraw-Hill, 2012
Buku Teks
edited by Jerrold R. Brandell
Free Press, 1997
Buku Teks
O`Sullivan, Terence
Macmillan, 1999
Buku Teks