Fox, Harrison W.
The Free Press, 1977
Buku Teks
Levin, Harvey J.
The John Hopkins Press,, 1971
Buku Teks
Llewelyn, David, author
Marshall Cavendish Business, 2010
Buku Teks
Wiener, Margaret j, author
The Univercity of Chicago Press, 1995
Buku Teks
Roever, Arend de, author
Pepin Press, 1996
Buku Referensi