1. Baader, F., Brandt, S., Lutz, C.: Pushing the
$\mathcal{EL}$
envelope. In: Proc. 19th Int. Joint Conf. on Artif. Intel. (IJCAI 2005), Edinburgh, UK. Morgan-Kaufmann Publishers (2005)
2. Baader, F., Brandt, S., Lutz, C.: Pushing the el envelope further. In: Clark, K., Patel-Schneider, P.F. (eds.) Proceedings of the OWLED 2008 DC Workshop on OWL: Experiences and Directions (2008)
3. Baader, F., Calvanese, D., McGuinness, D.L., Nardi, D., Patel-Schneider, P.F. (eds.): The Description Logic Handbook: Theory, Implementation, and Applications, 2nd edn. Cambridge University Press (2007)
4. LNAI;F. Bobillo,2013
5. LNAI;S. Borgwardt,2012