Jeanne H. Ballantine, Joan Z. Spade, editors
SAGE Publications, 2015
Buku Teks
McGraw-Hill , 1973
Buku Teks
International Labour Organisation
International Labour Organisation, 1983
Buku Referensi
Lawson, Hal A.
Allyn and Bacon, 1981
Buku Teks
Matthias Pilz
Springer-VS, 2012
eBooks