Kaufmann, Edgar
[T.t.] Horizon Press 1960
Buku Teks
Pareto, Vilfredo
Frederick A. Praeger, 1966
Buku Teks
edited by William R. Spriegel and Clark E. Myers
R.D. Irwin, 1953
Buku Teks
Brookes, Alan J.
Taylor &Fransic, 2008
Buku Teks
Lenczner, David
Pergamon Press, 1981
Buku Teks