Penguin Education, 1973
Buku Teks
Middlesex Penguin Books, 1971
Buku Teks
Saunders, Anthony
McGraw-Hill, 1997
Buku Teks
by Arthur J. Keown, John D. Martin, J. William Petty, David F. Scott
Prentice-Hall, 2001
Buku Teks
Prentice Hall International, 1991
Buku Teks