J. Tane. Formal Concept Analysis, Third International Conf., ICFCA 2005-Supplementary Volume, page 62--78. IUT de Lens, Universite d Artois, (February 2006)
R. Jäschke, A. Hotho, C. Schmitz, and G. Stumme. Proceedings of the 15th International Conference on Conceptual Structures, volume 4604 of LNCS, Sheffield, England, (July 2007)