Ott, Lyman
Duxbury Press, 1993
Buku Teks
Snedecor, George W.
Iowa State University Press, 1989
Buku Teks
Snedecor, George W.
The Iowa State University Press, 1980
Buku Teks
Snedecor, George W.
The Iowa State University Press, 1982
Buku Teks
Snedecor, George W.
The Iowa State University Press, 1950
Buku Teks SO