@article{JIS_2008__11_3_a6,
     author = {Bayon,  R. and Lygeros,  N.},
     title = {The hyperrings of order 3.},
     journal = {Journal of integer sequences},
     year = {2008},
     volume = {11},
     number = {3},
     zbl = {1152.16039},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2008__11_3_a6/}
}