1. N. I. Nikitin, Wood Chemistry [in Russian], Moscow-Leningrad (1951), p. 247.
2. H. Adkins and R. Frank, J. Am. Chem. Soc.,63, 549 (1940).
3. Z. A. Rogovin and N. N. Shorygina, The Chemistry of Cellulose and Its Accompanying Substances [in Russian], Moscow (1953), p. 607.
4. V. M. Nikitin and A. V. Obolenskaya, Bum. prom., No. 12, 1 (1953).
5. V. M. Nikitin, Lignin [in Russian], Leningrad (1961), p. 148.