1. Dana's System of Mineralogy, Vol. 1 (John Wiley & Sons, 1951) p. 780; R.V. Dietrich, in:Mineral Tables (McGraw Hill Book Company, New York, 1969).
2. R.W.G. Wyckoff, in:Crystal Structures, Vol. II (Interscience Publishers, Inc., New York, 1951).
3. International Tables for X-ray Crystallography, Vol. 1 (Kynoch Press, Birmingham, England, 1952).
4. J. Oliveira, C. Alves, Jr., C.A. Barros, R.A. Pereira and C.A. Santos, in:Proc. First Latin American Conference On The Applications of Mössbauer Effect Rio de Janeiro, 1988 (World Scientific Co, Singapore, 1990) p. 385.
5. N.E. Erickson, in: Advances In Chemistry Series No. 68.The Mössbauer Effect and Its Application In Chemistry (The American Chemical Society 1967, USA) p. 87.