Foster, George M., author
John Wiley & Sons, 1978
Buku Teks
Healey, Edwin F., author
Loyola University Press, 1956
Buku Teks
Pool, Robert, author
McGraw-Hill Open University Press, 2005
Buku Teks
Markell, Edward K., author
W.B. Saunders, 1992
Buku Teks
SEARO, 1998
Buku Teks