2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/64206It is proved that there exists a separable reflexive Banach space W that contains an isomorphic image of every separable superreflexive Banach space. This gives the affirmative answer on one J. Bourgain's questionLatex2e, the third, revised versionFunctional Analysis14B20 (Primary) 46A20, 46B03, 46B07, 46B10 (Secondary)text