1. Merewether, J. W. T., in Brauns, F. E., and Brauns, D. A., The Chemistry of Lignin, Supp. Vol., 630 (Academic Press, New York, 1960).
2. Kolboe, S., and Ellefsen, O., Tappi, 45, 163 (1962).
3. Tappi Standard T9m-54.
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5. Marton, J., Acta Chem. Scand., 15, 384 (1961).