Ryan, Daniel
Brooks / Cole Pub, 1983
Buku Teks
Dana, Forest C.
New York: McGraw-Hill, 1958
Buku Teks
Soderquist, Larry D.
Michie, 1991
Buku Teks
Whaley, Douglas J.
Little, Brown & Co., 1993
Buku Teks
Waddell, Joseph J.
McGraw-Hill, 1985
Buku Referensi