1. Encyclopedia of Geomagnetism and Paleomagnetism, Ed. by D. Gubbins and E. Herrero-Bervera (Springer, Berlin, 2007).
2. G. Podolsky and D. P. Keller, in Industrial Minerals and Rocks, Ed. by D. D. Carr, 6th ed. (Society for Mining, Metallurgy, and Exploration, Littleton, CO, United States 1994), p. 765.
3. L. C. Varanda, M. Jafelicci, Jr., and G. F. Goya, J. Magn. Magn. Mater. 226–230, 1933 (2001).
4. M. E. Evans and F. Heller, Environmental Magnetism: Principles and Applications of Enviromagnetics (Academic, San Diego, CA, United States, 2003).
5. J. M. D. Coey, A. Barryt, F. M. Brotto, H. Rakoto, S. Brennan, W. N. Musselt, A. Collomb, and D. Fruchar, J. Phys.: Condens. Matter 7, 759 (1995).