1. Allen, J.F., and P.J. Hayes. 1990. Moments and points in an interval-based temporal logic. Computational Intelligence 5(4):225–238.
2. Armstrong, D.M. 1997. A world of states of affairs. New York, NY: Cambridge University Press.
3. Ashburner, M., C.A. Ball, J.A. Blake, D. Botstein, H. Butler, J.M. Cherry, A.P. Davis, K. Dolinski, S.S. Dwight, J.T. Eppig, M.A. Harris, D.P. Hill, L. Issel-Tarver, A. Kasarskis, S. Lewis. et al. 2000. Gene ontology: Tool for the unification of biology. Nature Genetics 25(1):25–29.
4. Baader, F., D. Calvanese, D. McGuinness, D. Nardi, and P. Patel-Schneider, eds. 2003. The description logic handbook: Theory, implementation and applications. Cambridge, UK: Cambridge University Press.
5. Bachman, C.W., and M. Daya. 1977. The role concept in data models. In Proceedings of the 3rd International Conference on Very Large Databases, 464–476. IEEE Computer Society.