Watson, Hugh J., author
Businesss Publications , 1980
Buku Teks
edited by Barry G. Silverman
Addison-Wesley, 1987
Buku Teks
Lambourn, Simon
Longman, 1974
Buku Teks
Elison, Alan L.
Macmillan, 1991
Buku Teks
Shaw, Donald R
Van Nostrand Reinhald, 1981
Buku Teks