TY - JOUR AU - M. Yu. Zvyagin TI - Second order equations reducible to $z_{xy}=0$ by a B\"acklund transformation JO - Doklady Akademii Nauk PY - 1991 SP - 36 EP - 40 VL - 316 IS - 1 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/DAN_1991_316_1_a7/ LA - ru ID - DAN_1991_316_1_a7 ER -