Radim Belohlávek Bernard De Baets Jan Outrata Vilém Vychodil Characterizing Trees in Concept Lattices. 1-15 2008 16 International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems Supplement-1 http://dx.doi.org/10.1142/S0218488508005212 db/journals/ijufks/ijufks16.html#BelohlavekBOV08