Rodd, Laurel Rasplica
University of Hawaii , 1980
Buku Teks
University of Tokyo Press, 1984
Buku Teks
Laurel, J.B.
Philippine Panel, 1961
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