@article{10_4064_sm180_1_7,
     author = {Dana Gheorghe},
     title = {Stability of the index of a linear relation
 under compact perturbations},
     journal = {Studia Mathematica},
     pages = {95--102},
     publisher = {mathdoc},
     volume = {180},
     number = {1},
     year = {2007},
     doi = {10.4064/sm180-1-7},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm180-1-7/}
}