Barnet J. Richard
Simon and Schuster, 1980.
Buku Teks
Friederich, Carl J
Cornell University Press, 1957
Buku Teks
Hofstadter, Richard
Columbia University Press , 1955
Buku Teks
Byrne, J. Richard, author
McGraw-Hill , 1967
Buku Teks
Schonberger, Richard John, author
Business Publications, 1985
Buku Teks