International Labur Organization, c1977
Buku Teks
Loffel, Egon W.
John Wiley & Sons, 1977
Buku Teks SO
Pride, William M.
Hougton-Mifflin, 1988
Buku Teks
Czinkota, Michael R.
The Dryden Press , 1996
Buku Teks
Wormald, Avison
Pan Books, 1973
Buku Teks SO