Breen, George Edward, 1911-, author
McGraw-Hill , 1982
Buku Teks
Baker, Michael J., author
Macmillan, 1991
Buku Teks
Kress, George, author
Prentice-Hall, 1988
Buku Teks
Parasuraman, A., author
Addison-Wesley, 1991
Buku Teks
Aaker, David A., author
John Wiley & Sons, 1995
Buku Teks