Azagra Rueda, DanielFry, RobbKeener, L.2023-06-202023-06-2020100025-583110.1007/s00208-009-0441-6https://hdl.handle.net/20.500.14352/42082Let X be a Banach space with a separable dual X*. Let Y subset of X be a closed subspace, and f : Y -> R a C(1)-smooth function. Then we show there is a C(1) extension of f to X.engjournal articlehttp://www.springerlink.com/content/q165n777106362l7/fulltext.pdfrestricted access517.98Differentiable functionsclosed-setsc-mapproximationsubspacestheoremAnálisis funcional y teoría de operadores