@article{HellwigVolkmann2013,
  author    = {Angelika Hellwig and Lutz Volkmann},
  title     = {Lower bounds on the vertex-connectivity of digraphs and graphs},
  journal   = {Information processing letters},
  volume    = {Vol. 99},
  number    = {Iss. 2},
  pages     = {41 -- 46},
  year      = {2013},
}