Martin, William J., author
Aslib Gower, 1995
Buku Teks
Martin, William J., author
Brookfield, Vt., USA : Gower,, 1995.
Buku Teks
Currie, Wendy, author
John Wiley & Sons, 2000
Buku Teks
Barber, William J.
Stanford University, 1961
Buku Teks
Voich, Dan, author
South-Western Publishing Co, 1975
Buku Teks