00529naa#a2200181#i#450# EN\INFRA-M\bibl\28045 20240508160209.3 2308-4898 20190408b2019####ek#y0engy0150####ca RUS RU General Principles for Formation of Ruled Surfaces. Part 2 Journal article Moscow INFRA-M Academic Publishing LLC. 2019 13 с. Journal article local Математика. 51 RUS Sal'kov N. A. riorpub.com