Mathematical notes of the Academy of Sciences of the USSRMay 1977, Volume 21, Issue 5, pp 335–335 | Cite asBirthdayAuthorsAuthors and affiliationsAleksei Fedorovich Leont'evArticle 24 Downloads This is a preview of subscription content, log in to check access.Copyright information© Plenum Publishing Corporation 1977Authors and AffiliationsAleksei Fedorovich Leont'evThere are no affiliations available