Schultz, Theodore W.
Yale University Press , 1964
Buku Teks
Schultz, Theodore W.
The Minchigan of Univ. Press, 1966
Buku Teks
Snedecor, George W., author
The Iowa State University Press, 1962
Buku Teks
Schultz, Theodore W.
McGraw-Hill , 1945
Buku Teks
Mead, R., author
Chapman & Hall, 1993
Buku Teks