@article{etna_vol37_pp337-350,
  author  = {Jonathan J. Crofts and Ernesto Estrada and Desmond J. Higham and Alan Taylor},
  title   = {Mapping directed networks},
  journal = {Electron. Trans. Numer. Anal.},
  volume  = {37},
  year    = {2010},
  pages   = {337--350},
}