1. “Preparation of ammoniated lignin”;Abduazimov;Gidroliz. Lesokhim. Prom-st.,1979
2. “Industrial development of furfural”;Brownlee;lnd. Eng. Chem.,1948
3. Bratzler , K. H. Schaefer G. Hingst P. Aalrust “Organic substances rich in N, special organic fertilizers” 1964
4. Bratzler , K. H. Schaefer “Artificial organic-inorganic fertilizer” 1971
5. Chudakov , M. I. 1968