Neil Immerman
Relational Queries Computable in Polynomial Time
STOC, 1982.
@inproceedings{STOC-1982-Immerman, author = "Neil Immerman", booktitle = "{Proceedings of the 14th Annual ACM Symposium on Theory of Computing}", doi = "10.1145/800070.802187", isbn = "0-89791-067-2", pages = "147--152", publisher = "{ACM}", title = "{Relational Queries Computable in Polynomial Time}", year = 1982, }