Raykov, Tenko
Routledge, Taylor & Francis Group, 2008
Buku Teks
Tabachnick, Barbara G.
Allyn and Bacon, 2001
Buku Teks
Cooley, William W.
John Wiley & Sons, 1971
Buku Teks
Hardle, Wolfgang Karl
Springer, 2012
eBooks
Cooley, William W.
Robert E. Krieger, 1986
Buku Teks