Schwarz, Stephen
West Publishing, 1994
Buku Teks
Smith, Dan Throop
Boston Harvard University 1952,
Buku Teks
F. Damian Leo
Kluwer, 1978
Buku Teks
Butters, J. Keith
Harvard University Press , 1951
Buku Teks
Brown, Kenneth S., author
Springer-Verlag, 1982
Buku Teks