Downes, John
Barron's Educational Series, 1998
Buku Referensi
Hildreth, Sandra S.
Dearborn Financial Publishing, 1988
Buku Referensi
Oxford University Press, 1993
Buku Referensi
Salman, S.L.
S.S. Mubaruk and Brothers, 1994
Buku Teks
Pence, Gregory E.
McGraw-Hill, 2000
Buku Teks