@inproceedings{Niemela:ICLP08,
author = {Ilkka Niemel{\"a}},
booktitle = {Proceedings of the 24th International Conference on Logic Programming (ICLP 2008)},
pages = {88--92},
publisher = {Springer},
series = {Lecture Notes in Computer Science},
title = {Answer Set Programming without Unstratified Negation},
volume = {5366},
year = {2008},
}