Field, Andy P., author
SAGE Publications, 2016
Buku Teks
Heck, Ronal H., author
Routledge, 2014
Buku Teks
Norusus, Marija, author
SPSS Inc, 1990
Buku Teks
Puotinen, C.J., author
Holt, Rinehart and Winston, 1983
Buku Teks
Green, Samuel B., author
Prentice-Hall, 2000
Buku Teks