Rollins, Dan, author
Macmillan, 1985
Buku Teks
Norton, Peter, author
[publisher not identified], [date of publication not identified]
Buku Teks
Universitas Indonesia, 1995
UI - Tugas Akhir
Norusus, Marija, author
SPSS Inc, 1990
Buku Teks
Iik Wilarso, author
Elex Media Komputindo, 1989
Buku Teks