Adkins, Dorothy C.
Charles E. Merrill Books , 1964
Buku Teks
Samuel, Myra L.
Pearson - Prentice Hall, 2003
Buku Teks
Schork, M. Anthony
Prentice-Hall, 2000
Buku Teks
Larsen, Richard J.
Prentice-Hall, 1996
Buku Teks
Kaplan, Robert M.
Allyn and Bacon , 1987
Buku Teks