Heaton, Russell, author
Blackstone, 1998
Buku Referensi
Sackville, Ronald, author
Butterworth, 1975
Buku Teks
Adelman, Martin J., author
Thomson/West, 2009
Buku Teks
Boswell, Richard A., author
Carolina Academic Press, 1992
Buku Teks
Jamil S. Zainaldin
St.Paul, Minn., 1980
Buku Teks