Ehrenberg, Ronald G., author
Pearsons Addison-Wesley , 2009
Buku Teks
McConnell, Campbell R., author
McGraw-Hill, 1989
Buku Teks
International Labour Office, 2017
Majalah, Jurnal, Buletin
Brooks, Brian S., author
Tax and Business Law Publishers, 1990
Buku Teks
Reynolds, Lloyd G., author
Prentice-Hall, 1998
Buku Teks