Still, Richard R.
Prentice-Hall, 1988
Buku Teks
Quelsch, John A.
Prentice-Hall, 1989
Buku Teks
Hoffamn, K. Douglas
Horcourt Colledge Publisher, 2002
Buku Teks
Terry, George Robert, author
Prentice-Hall, 1957
Buku Teks
Johnson, Lewis K., author
Allyn and Bacon, 1957
Buku Teks