Deletion of Ivan Pervushin

Comment: The Russian Wikipedia article has convincing sources for  (in two Russian-language print encyclopedias, but sources don't need to be in English). I also found what appears to be a journal article about him, but only by reference (I haven't found the article itself): A. E. Raik. Ural'skii matematik Ivan Mikheevich Pervushin. ''Istoriko-Matematicheskie Issledovaniya'' 6 (1953). 535-572
Stance: keep
Cited policy: Wikipedia:Notability (WP:GNG)