00554naa#a2200181#i#450# EN\INFRA-M\bibl\17349 20240516080508.4 2308-4898 20170704b2017####ek#y0engy0150####ca RUS RU Conics As Sections of Quadrics by Plane (Generalized Dandelin Theorem) Journal article Moscow INFRA-M Academic Publishing LLC. 2017 13 с. Journal article local Математика. 51 RUS Kheyfets Aleksandr L'vovich naukaru.ru