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2. P. G. JEFFREY, Chemical Methods of Rock Analysis, Pergamon Press New York, 2nd ed. 1975, p. 130.
3. P. G. JEFFREY, Chemical Methods of Rock Analysis, Pergamon Press, New York, 2nd ed. 1975, p. 2.
4. G. F. KIRKBRIGHT, M. SARGENT, Atomic Absorption and Fluorescence Spectroscopy, Academic Press, New York, 1974.
5. E. P. BERTIN, Principles and Practice of X-ray Spectrometric Analysis 2nd ed., Plenum Press, New York, 1975.