Fraser, Cynthia, author
Springer, 2012
eBooks
Kirkpatrick, Lee A., author
Wadsworth and Cengage Learning, 2011
Buku Teks
Rijanto Tosin, author
Dinastindo, 1990
Buku Teks
Porter, Alan G.
Reading, Mass.: Addison-Wesley, c1985
Buku Teks
Norusus, Marija, author
SPSS Inc, 1990
Buku Teks