@article{JAC_2006__24_1_a4,
     author = {Babson, Eric and Barcelo, H\'el\`ene and de Longueville, Mark and Laubenbacher, Reinhard},
     title = {Homotopy theory of graphs},
     journal = {Journal of Algebraic Combinatorics},
     pages = {31--44},
     publisher = {mathdoc},
     volume = {24},
     number = {1},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JAC_2006__24_1_a4/}
}