@article{JAC_2009__30_4_a9,
     author = {Herzog, J\"urgen and Hibi, Takayuki and Ohsugi, Hidefumi},
     title = {Unmixed bipartite graphs and sublattices of the {Boolean} lattices},
     journal = {Journal of Algebraic Combinatorics},
     pages = {415--420},
     publisher = {mathdoc},
     volume = {30},
     number = {4},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JAC_2009__30_4_a9/}
}