00528naa#a2200181#i#450# EN\INFRA-M\bibl\29909 20241220101531.5 2308-4898 20190815b2019####ek#y0engy0150####ca RUS RU General Principles for Formation of Ruled Surfaces. Part 3 Journal article Moscow INFRA-M Academic Publishing LLC. 2019 14 с. Journal article local Математика. 51 RUS Sal'kov N. A. naukaru.ru