Ewen, David, author
Prentice Hall, 1968
Buku Referensi
Day, Paul W
Twayne Publishers , 1968
Buku Teks
Kelter, Paul B., author
McGraw-Hill, 2003
Buku Teks
Avison, John
T. Nelson Australia [distributor , 1989
Buku Teks
Harder, Paul O
Allyn and Bacon , 1975
Buku Teks