Murray, James D.
O’Reilly & Associates, 1994
Buku Referensi
Hill, Francis S., author
Macmillan, 1990
Buku Teks
Hearn, Donald, author
Prentice-Hall, 1986
Buku Teks
Rogers, David F., 1937-, author
McGraw-Hill , 1990
Buku Teks
Walker, B.S., author
Crane Russak, 1975
Buku Teks