1. E.F. Stoermer, J.P. Smol, The Diatoms: Applications for the Environmental and Earth Sciences (Cambridge University Press, Cambridge, 2001), pp. 436–443
2. P. Yuan, D. Yang, Z. Lin, H. He, X. Wen, L. Wang, F. Deng, J. Non-Cryst. Solids 352, 3762 (2006)
3. P. Yuan, D.Q. Wu, H.P. He, Z.Y. Lin, Appl. Surf. Sci. 227, 30 (2004)
4. U.S Department of the Interior, U.S. Geological Survey, Mineral Commodity Summaries 2014 (U.S. Geological Survey, Virginia, 2014), p. 53
5. A. Michels, Rev. Biol. Trop. 46, 143 (1998)