Manser, W.A.P.
Cassell/Associated Business Programmes, 1973
Buku Teks
Oecd, author
OECD Publishing, 2001
Buku Teks
Dunning, John H
Addison-Wesley , 1992
Buku Teks
Vernon, Raymond, author
Basic Books, 1971
Buku Teks
Baumgartner, Wilfrid S.
Paris , International Chamber of Commerce
Buku Teks