1. E. B. Sandell, Colorimetric Determination of Traces of Metals. 2nd Ed. New York: Interscience,1950. S.512.
2. K. Gardner, Analyst76, 485 (1951).
3. Gyula Almassy undP�l Szarvas, Tudom�nyok Oszt�ly�ok Kozlemenyei3, 413 (1953); durch Chem. Abstr.1955, 5205.
4. Arno?t Oka? undL. Somner, Chem. Listy47, 659 (1953); durch Chem. Abstr.1954, 3189.
5. S. I. Gusev undR. G. Beiles, Otdel. Khim. Nauk5 (8), 68 (1954); durch Chem. Abstr.1955, 12190.