BibTeX

@ARTICLE{iumj17040,
    author = "William Stenger",
     title = "On the Variational Principles for Eigenvalues for a Class of Unbounded Operators",
   journal = "Indiana Univ. Math. J.",
  fjournal = "Indiana University Mathematics Journal",
    volume = 17,
      year = 1968,
     issue = 7,
     pages = "641--648",
      issn = "0022-2518",
     coden = "IUMJAB",
   mrclass = "",
}

amsrefs

\bib{iumj17040}{article}{
     author = {Stenger, William},
      title = {On the Variational Principles for Eigenvalues for a Class of Unbounded Operators},
    journal = {Indiana Univ. Math. J.},
     volume = {17},
       year = {1968},
     number = {7},
      pages = {641 \ndash 648},
}