@article{AngerGebserSchaub2006,
  author    = {Anger, Christian and Gebser, Martin and Schaub, Torsten H.},
  title     = {Approaching the core of unfounded sets},
  year      = {2006},
  language  = {en}
}
@article{AngerGebserJanhunenetal.2006,
  author    = {Anger, Christian and Gebser, Martin and Janhunen, Tomi and Schaub, Torsten H.},
  title     = {What's a head without a body?},
  year      = {2006},
  language  = {en}
}