@inproceedings{AAAI-2016-obda-beyond-ql,
   title    = {Beyond OWL 2 QL in OBDA: Rewritings and Approximations},
   year     = {2016},
   author   = {Elena Botoeva and Diego Calvanese and Valerio Santarelli and Domenico Fabio Savo and Alessandro Solimando and Guohui Xiao},
   booktitle = {Proc. of the 30th AAAI Conf. on Artificial Intelligence (AAAI 2016)},
   publisher = {AAAI Press},
   pages     = {921-928},
   webpdf = {http://www.inf.unibz.it/~ebotoeva/papers/bcsssx-AAAI-16.pdf},
}