J. Tane. Formal Concept Analysis, Third International Conf., ICFCA 2005-Supplementary Volume, page 62--78. IUT de Lens, Universite d Artois, (February 2006)
G. Stumme. Conceptual Structures: Knowledge Representation as Interlingua Proc. ICCS'96, volume 1115 of LNAI, page 308-320. Heidelberg, Springer, (1996)
F. Lehmann, and R. Wille. Conceptual structures: applications, implementation and theory, 954, page 32-43. Berlin--Heidelberg--New~York, Springer--Verlag, (1995)