Martin Grohe, Thomas Schwentick, Luc Segoufin. When is the evaluation of conjunctive queries tractable?. In STOC. pages 657-666, 2001. [doi]
@inproceedings{GroheSS01,
title = {When is the evaluation of conjunctive queries tractable?},
author = {Martin Grohe and Thomas Schwentick and Luc Segoufin},
year = {2001},
doi = {10.1145/380752.380867},
url = {http://doi.acm.org/10.1145/380752.380867},
researchr = {https://researchr.org/publication/GroheSS01},
cites = {0},
citedby = {0},
pages = {657-666},
booktitle = {STOC},
}