George, Thomas F
Prentice-Hall, 1987
Buku Teks
Griffin, Ricky W.
Pearson Education International, 2006
Buku Teks
Griffin, Ricky W.
Prentice-Hall, 1999
Buku Teks
Griffin, Ricky W.
Prentice-Hall, 2002
Buku Teks
Wheeler, Bayard O.
Harper & Row. Publisher, 1968
Buku Teks