R. Jäschke, A. Hotho, C. Schmitz, B. Ganter, и G. Stumme. Proceedings of the 6th IEEE International Conference on Data Mining (ICDM 06), стр. 907-911. Hong Kong, IEEE Computer Society, (Декабрь 2006)
F. Lehmann, и R. Wille. Conceptual structures: applications, implementation and theory, 954, стр. 32-43. Berlin--Heidelberg--New~York, Springer--Verlag, (1995)