@article{10_4064_sm_129_3_253_264,
     author = {Thorsten Kr\"oncke},
     title = {Extremal perturbations of {semi-Fredholm} operators},
     journal = {Studia Mathematica},
     pages = {253--264},
     publisher = {mathdoc},
     volume = {129},
     number = {3},
     year = {1998},
     doi = {10.4064/sm-129-3-253-264},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-129-3-253-264/}
}