1. PALACHE, C., BERMAN, H., and FRONDEL, C. The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, 7th edn, John Wiley & Sons, Inc., New York (1946) 255-258.
2. HOWIE, F. M., ed. The Care and Conservation of Geological Material: Minerals, Rocks, Meteorites and Lunar Finds, Butterworth- Heinemann Ltd, Oxford (1992) 63.