@article{10_4153_CMB_1973_025_7,
     author = {Marsden, J.},
     title = {A {Proof} of the {Calderon} {Extension} {Theorem}},
     journal = {Canadian mathematical bulletin},
     pages = {133--136},
     year = {1973},
     volume = {16},
     number = {1},
     doi = {10.4153/CMB-1973-025-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1973-025-7/}
}