Bradgate, Robert
Butterworth, 1991
Buku Teks
Adams, Kristen David
St. Paul, MN : West Group, 2010
Buku Teks
Macintryre, Ewan
Blackstone Press, 1998
Buku Referensi
Ryder, Nicholas
Cambridge University Press , 2012
Buku Teks
Hung, William S.H.
[Publisher not identified], 1932
Buku Teks