1. Adams, P. B., and C. H. North: I. Material Res. Sympos. Gaithersburg 1966, Paper No. 13.
2. Ahrens, L. H.: Geochim. Cosmochim. Acta 5, 49 (1954).
3. Alimarin, I. P.: Uspechi Chim. 4, 854 (1935).
4. ASTM standard method E-135, Methods of emission spectrochemical analysis, p. 117. Philadelphia: ASTM 1964.
5. Boumans, P. W. J. M., u. F. J. M. J. Maessen: diese Z. 220, 241 (1966).