TY - JOUR AU - I. A. Kruglov AU - I. V. Cherednik TI - On the existence of non-negative bases in subgroups of free groups of Schreier varieties JO - Matematičeskie voprosy kriptografii PY - 2019 SP - 53 EP - 65 VL - 10 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/MVK_2019_10_a3/ LA - ru ID - MVK_2019_10_a3 ER -