Certo, Samuel C.
Prentice Hall International, 1997
Buku Teks
Johnson, Ross H., author
Houghton Miffiln, 1976
Buku Teks
McFarland, Dalton E., author
Collier Macmillan, 1974
Buku Teks
Cabell, Randolph W.
John Wiley & Sons, 1961
Buku Teks
Certo, Samuel C., author
Pearson , 2009
Buku Teks