00461naa#a2200169#i#450# EN\INFRA-M\bibl\10832 20241218182231.3 2308-4898 20160317b2016####ek#y0engy0150####ca ENG RU Roof Skeletons and Graph Theory Trees Journal article Moscow INFRA-M Academic Publishing LLC. 2016 8 с. Journal article local Kozniewski E. naukaru.ru