Macintryre, Ewan
Blackstone Press, 1998
Buku Referensi
Countryman, Vern
Little, Brown, 1971
Buku Teks
Corman, Calvin W.
Little,Brown and Company, 1983
Buku Teks
Schlesinger, Rudolf B.
The Foundation Press, 1950
Buku Teks
Kauper, Paul G.
Little, Brown, 1971
Buku Teks