@inproceedings{DBLP:conf/lpnmr/GebserLL07,
  author = {Gebser, Martin and Lee, Joohyung and Lierler, Yuliya},
  title = {Head-Elementary-Set-Free Logic Programs},
  booktitle = {{LPNMR}},
  series = {Lecture Notes in Computer Science},
  volume = {4483},
  pages = {149--161},
  publisher = {Springer},
  year = {2007}
}