R. Jäschke, A. Hotho, C. Schmitz, B. Ganter, and G. Stumme. Proceedings of the 6th IEEE International Conference on Data Mining (ICDM 06), page 907-911. Hong Kong, IEEE Computer Society, (December 2006)
B. Ganter, and G. Stumme. Conceptual Structures for Knowledge Creation and Communication., volume 2746 of LNAI, page 131-145. Heidelberg, Springer, (2003)