Michie, 1996
Buku Teks
Butterworth Legal Publishers, 1993
Buku Teks
Philip, George
George Philip & Son, 1959
Buku Teks
Czinkota, Michael R., author
The Dryden Press, 1994
Buku Teks
Mason, R. Hal (Robert Hal), 1929-, author
John Wiley & Sons, 1981
Buku Teks