Jones, John G.
Alexander Hamilton Institute, 1961
Buku Teks
Still, Richard R.
Prentice Hall International, 1988
Buku Teks
Spiro, Rosann L.
McGraw-Hill-Irwin, 2003
Buku Teks
Stanton, William J.
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Buku Teks
Voe, Merrill De
Prentice-Hall, 1957
Buku Teks