00505naa#a2200169#i#450# EN\INFRA-M\bibl\46783 20251207110235.7 2308-4898 20211111b2021####ek#y0engy0150####ca RU The Main Reasons for Poor Assimilation of Descriptive Geometry Journal article Moscow INFRA-M Academic Publishing LLC. 2021 8 с. Journal article local Математика. 51 Sal'kov N. A. zh-szf.ru