Black, Tyrone
Business Publications, Inc., 1981
Buku Teks
Shapiro, Eli, author
Holt, Rinehart and Winston,Inc., 1968
Buku Teks
Pesek, Boris P., author
Harvester. Wheatshaf, 1988
Buku Teks
Prager, Jonas, author
Harper & Row, 1982
Buku Teks
Campbell, Colin D., author
The Dryden , 1983
Buku Teks