Fox, John P., author
Macmillan, 1970
Buku Teks
Nelson, Kenrad E., author
Jones and Bartlett Publisher, 2005
Buku Teks
Duncan, David F.
Macmillan, 1988
Buku Teks
Robinson, Derek
Churchill Livingstone, 1985
Buku Teks
Peterson, Donald R.
Massachusetts Lexington Books, 1978
Buku Teks