Schuster, Frederick E., author
Reston, 1985
Buku Teks
Saltonstall, Robert, author
McGraw-Hill, 1959
Buku Teks
Gorman, Paul
Kogan Page, 1998
Buku Teks
edited by Henry C. Metcalf and L.F. Urwick
Harper & Brother , 1940
Buku Teks
Cook, Mary F., author
Prentice-Hall, 1997
Buku Referensi