Process for chlorine-free bleaching of kraft hardwood cellulose / A. N. Zakazov, E. N. Medvedeva, V. A. Babkin [et.al.] // Fundamental and applied problems of environmental protection. Vol. 3 : International conference, September, 12-16, 1995, Tomsk : abstracts. Tomsk, 1995. Vol. 3 : Physical-chemical methods of environmentalal monitoring. P. 151