@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}, zbl = {0154.15802}, mrnumber = {203461}, language = {en}, url = {archive.numdam.org/item/RSMUP_1966__36_2_217_0/} }
Coburn, L. A.; Lebow, A. Approximation by Fredholm operators in the metric space of closed operators. Rendiconti del Seminario Matematico della Università di Padova, Tome 36 (1966) no. 2, pp. 217-222. http://archive.numdam.org/item/RSMUP_1966__36_2_217_0/
[1] Algebraic theory of Fredholm operators. Jour. Math. Mech. (to appear). | Zbl 0143.16003
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and :