@article{10_4064_sm146_3_1,
     author = {C. J. Atkin},
     title = {Extension of smooth functions in infinite dimensions, {I:
} unions of convex sets},
     journal = {Studia Mathematica},
     pages = {201--226},
     publisher = {mathdoc},
     volume = {146},
     number = {3},
     year = {2001},
     doi = {10.4064/sm146-3-1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm146-3-1/}
}