1. Abiteboul S, Hull R, Vianu V (1995) Foundations of Databases. Addison Wesley, Reading, MA
2. Baader F (1990) Terminological cycles in KL-ONE-based knowledge representation languages. In: Proc of the 8th Nat Conf on Artificial Intelligence (AAAI’90), 29 July–3 August 1990, Boston, MA, USA, pp 621–626
3. Baader F, Brandt S, Lutz C (2005) Pushing the EL envelope. In: Kaelbling LP, Saffiotti A (eds) Proc of the 19th Int Joint Conf on Artificial Intelligence (IJCAI 2005), 30 July–5 August 2005, Edinburgh, UK. Morgan Kaufmann, Los Altos, pp 364–369
4. Baader F, Brandt S, Lutz C (2008) Pushing the EL envelope further. In: Clark K, Patel-Schneider PF (eds) Proc of the Fifth International Workshop on OWL: Experiences and Directions (OWLED’08), 26–27 October 2008, Karlsruhe, Germany
5. Baader F, Calvanese D, McGuinness D, Nardi D, Patel-Schneider PF (eds) (2003) The Description Logic Handbook: Theory, Implementation, and Applications. Cambridge University Press