BibTeX

@ARTICLE{iumj4107,
    author = "Igor Klep and Markus Schweighofer",
     title = "Pure states, positive matrix polynomials and sums of hermitian squares",
   journal = "Indiana Univ. Math. J.",
  fjournal = "Indiana University Mathematics Journal",
    volume = 59,
      year = 2010,
     issue = 3,
     pages = "857--874",
      issn = "0022-2518",
     coden = "IUMJAB",
   mrclass = "15A48; 11E25; 13J30; 15A54; 14P10; 46A55;",
}

amsrefs

\bib{iumj4107}{article}{
     author = {Klep, Igor},
     author = {Schweighofer, Markus},
      title = {Pure states, positive matrix polynomials and sums of hermitian squares},
    journal = {Indiana Univ. Math. J.},
     volume = {59},
       year = {2010},
     number = {3},
      pages = {857 \ndash 874},
}