Posner, Richard A.
The University of Chicago, 1976
Buku Teks
edited by Sylvester E. Berki
Health, 1966
Buku Teks
Hylton, Keith N, Author
Cambridge University Press, 2003
eBooks
Fox, Eleanor M.
Thomson Reuters, 2010
Buku Teks
Elzinga, Kenneth G.
Yale University Press, 1976
Buku Teks