@article{BUMI_1959_3_14_1_a9,
     author = {Bellman, Richard},
     title = {On the variation of the {Fredholm} resolvent.},
     journal = {Bollettino della Unione matematica italiana},
     pages = {78--81},
     publisher = {mathdoc},
     volume = {Ser. 3, 14},
     number = {1},
     year = {1959},
     zbl = {0088.08102},
     mrnumber = {130543},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/BUMI_1959_3_14_1_a9/}
}