Sources
Meissner, Rolf. The Little Book of Planet Earth. United States: Copernicus Books, 2002.
Jonkers, A.R.T. Earth’s Magnetism in the Age of Sail. United States: The Johns Hopkins University Press, 2003.
Merrill, Ronald and McElhinny, Michael. The Earth’s Magnetic Field. London: Academic Press Inc., 1983.
Backus, George and Parker, Robert and Constable, Catherine. Foundations of Geomagnetism. United States: Cambridge University Press, 1996.
Luhr, James. Smithsonian Earth. United States: DK Publishing, 2007.
Magnetic Field. <http://en.wikipedia.org/wiki/Magnetic_field>
Curie Temperature. <http://en.wikipedia.org/wiki/Curie_temp>