@article{10_4064_sm_52_1_1_8,
     author = {Robert Israel},
     title = {Perturbations of {Fredholm} operators},
     journal = {Studia Mathematica},
     pages = {1--8},
     publisher = {mathdoc},
     volume = {52},
     number = {1},
     year = {1974},
     doi = {10.4064/sm-52-1-1-8},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-52-1-1-8/}
}