1. U.S. Department of the Interior, U.S. Geological Survey, National Minerals Information Center, 2016. http://minerals.usgs.gov/minerals/, Retrieved August 29, 2016.
2. H. H. Schaumann, Production of titanium oxide pigments, 1949, (U.S. Patent 2,488,439A).
3. I.J. Krchma, H.H. Schaumann, Production of titanium dioxide, 1951, (U.S. Patent 2,559,638A).
4. S.E. Pratsinis, S. Vemury, G.P. Fotou, A. Gutsch, Process for producing ceramic powders, especially titanium dioxide useful as a photocatalyst, 1997, (U.S. Patent 5,698,177A).
5. A.J. Morris, M.D. Coe, System for increasing the capacity of a titanium dioxide producing process, 1989, (U.S. Patent 4,803,056A).