http://pec.lib.wvu.edu/record/P177521938Determination of small amounts of potassium : a simpler and more rapid variation of the sodium cobaltinitrite method.Journal article reprint from: <em>Industrial and Engineering Chemistry</em>, v.10 (1938:Nov.15).Robinson, R. R.Brown, D. S.Browning, George Monroe, 1908-Potassium.Chemical tests and reagents.14256