@article{etna_vol40_pp82-93,
  author  = {Aleksandra Kosti\'c and Heinrich Voss},
  title   = {On Sylvester's law of inertia for nonlinear eigenvalue problems},
  journal = {Electron. Trans. Numer. Anal.},
  volume  = {40},
  year    = {2013},
  pages   = {82--93},
}