P. Cimiano, A. Hotho, G. Stumme, and J. Tane. Concept Lattices, volume 2961 of LNAI, page 189-207. Heidelberg, Second International Conference on Formal Concept Analysis, ICFCA 2004, Springer, (2004)
A. Hotho, A. Maedche, and S. Staab. Proc. of the Workshop ``Text Learning: Beyond Supervision'' at IJCAI 2001. Seattle, WA, USA, August 6, 2001, (2001)