Flewitt, P.E.J.
Institute of Physical, 1994
Buku Teks SO
Shryock, Henry S.
Academic press, 1976
Buku Teks SO
Wass, Alonzo
Reston, VA: Reston Publishing, 1973
Buku Teks
Campbell, Enid Mona
[Publisher not identified], [Date of publication not identified]
Buku Teks
Campbell, Enid Mona
The Law Book, 1967
Buku Teks SO