F. Lehmann, и R. Wille. Conceptual structures: applications, implementation and theory, том 954 из Lecture Notes in Artificial Intelligence, стр. 32-43. London, UK, Springer Verlag, (1995)
K. Becker, G. Stumme, R. Wille, U. Wille, и M. Zickwolff. Knowledge Engineering and Knowledge Management. Methods, Models, and Tools., том 1937 из LNAI, стр. 352-365. Heidelberg, Springer, (2000)