1. R. Vanossi, Anales soc. cient. Argentina139, 29 (1945).
2. E. B. Sandell, Colorimetric Determination of Traces of Metals, 2nd ed., p. 334. New York: Interscience Publ. 1950.
3. H. Newcombe, W. A. E. Mocryde, J. Bartlett andF. E. Beamish, Analyt. Chemistry23, 1023 (1951).
4. W. Biltz undW. Fischer, Ausführung qualitativer Analysen anorganischer Stoffe, 11th edn., p. 167. Leipzig. 1952.
5. W. Fischer andW. Harre, private communication, 1953; cf.Fischer andHarre, Angew. Chem.64, 600 (1952).