Academy Editions, 1993
Buku Teks
Kaufmann, Edgar
[T.t.] Horizon Press 1960
Buku Teks
Pareto, Vilfredo, author
Frederick A. Praeger, 1966
Buku Teks
edited by William R. Spriegel and Clark E. Myers
R.D. Irwin, 1953
Buku Teks
Brookes, Alan J., author
Taylor &Fransic, 2008
Buku Teks