00467naa#a2200169#i#450# EN\INFRA-M\bibl\37112 20240522053729.3 2308-4898 20200420b2020####ek#y0engy0150####ca RU Dual Problems with Conics Journal article Moscow INFRA-M Academic Publishing LLC. 2020 9 с. Journal article local Математика. 51 Girsh A. G. naukaru.ru