BibTeX

@ARTICLE{iumj12047,
    author = "H. Cordes and J. Labrousse",
     title = "The Invariance of the Index in the Metric Space of Closed Operators",
   journal = "Indiana Univ. Math. J.",
  fjournal = "Indiana University Mathematics Journal",
    volume = 12,
      year = 1963,
     issue = 5,
     pages = "693--719",
      issn = "0022-2518",
     coden = "IUMJAB",
   mrclass = "",
}

amsrefs

\bib{iumj12047}{article}{
     author = {Cordes, H.},
     author = {Labrousse, J.},
      title = {The Invariance of the Index in the Metric Space of Closed Operators},
    journal = {Indiana Univ. Math. J.},
     volume = {12},
       year = {1963},
     number = {5},
      pages = {693 \ndash 719},
}