Marshall, P.T.
Mac Donald and Evans, 1974
Buku Teks
Wrensch, Dana L., author
Kendall/Hunt, 1992
Buku Teks
Mader, Sylvia S., author
McGraw-Hill , 1998
Buku Teks
Case, James F., author
Macmillan, 1979
Buku Teks
Ritchie, Donald D., author
Addison-Wesley, 1983
Buku Teks