Ruiter, Dick W. P., author
Kluwer Academic, 2001
Buku Teks
edited by Monrad G. Paulsen
Columbia University Press, 1959
Buku Teks
Cambridge University Press, 2015
eBooks
Lev, Daniel S., author
University of California Press, 1972
Buku Teks
The Free Press of Glencoe, 1964
Buku Teks