TY JOUR TI Typology and legal regulation of digital platforms KW digital platform KW transactional platforms KW non-transactional platforms KW marketplaces KW platform economy KW legal regulation KW intermediary platform KW typology KW digital ecosystem JO Society, law, statehood: retrospective and perspective AU Churikova, A.Y. PY 2026 IS 2026 PB Ufa Law Institute of the Ministry of Internal Affairs of Russia