@article{etna_vol31_pp295-305,
  author  = {Hubert Schwetlick and Kathrin Schreiber},
  title   = {A counterexample for characterizing an invariant subspace of a matrix},
  journal = {Electron. Trans. Numer. Anal.},
  volume  = {31},
  year    = {2008},
  pages   = {295--305},
}