1. Pushing the EL envelope;Baader,2005
2. F. Baader, S. Brandt, C. Lutz, Pushing the EL envelope further, in: K. Clark, P.F. Patel-Schneider (Eds.), Proceedings of the OWLED 2008 DC Workshop on OWL: Experiences and Directions.
3. The Description Logic Handbook: Theory, Implementation, and Applications,2003
4. F. Baader, C. Lutz, B. Suntisrivaraporn, Is tractable reasoning in extensions of the description logic EL useful in practice?, in: Proceedings of the Methods for Modalities Workshop (M4M-05), Berlin, Germany.
5. Solving time-dependent planning problems;Boddy,1989