@article{RSMUP_1966__36_2_217_0,
     author = {Coburn, L. A. and Lebow, A.},
     title = {Approximation by {Fredholm} operators in the metric space of closed operators},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {217--222},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {36},
     number = {2},
     year = {1966},
     mrnumber = {203461},
     zbl = {0154.15802},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1966__36_2_217_0/}
}