O`Hagan, David
Ellis Horwood Limited, 1991
Buku Teks
Helwig, David
General Publishing Co., 1983
Koleksi Publik
Colander, David C., author
McGraw-Hill , 1998
Buku Teks
Golbett, David
Universty of Taronto Press, Universty of Taronto Press, 1965
Buku Teks
Dolowitz, David A.
McGraw-Hill, 1964
Buku Teks