Derfler, Frank J., author
Ziff-Davis Press, 1992
Buku Teks
Mason, Peter, author
Routledge, 1998
Buku Teks
Gurewich, Nathan, author
McGraw-Hill, 1992
Buku Teks
Anis, Nick, author
Osborne-McGraw-Hill , 1991
Buku Teks
Norusus, Marija, author
SPSS Inc, 1990
Buku Teks