Roebuck, Deborah Britt, author
Business Expert Press, 2012
Buku Teks
Treece, Marla, author
Allyn and Bacon, 1994
Buku Teks
Machin, John L.J., author
McGraw-Hill, 1980
Buku Teks
Munter, Mary, author
Prentice-Hall, 1982
Buku Referensi
Duerr, Carl
Pan Books , 1973
Buku Teks