@article{SEMR_2008_5_a19,
     author = {A. A. Dobrynin and L. S. Mel'nikov},
     title = {Two series of edge-$4$-critical {Gr\"otzsch--Sachs} graphs generated by four curves in the plane},
     journal = {Sibirskie \`elektronnye matemati\v{c}eskie izvesti\^a},
     pages = {255--278},
     publisher = {mathdoc},
     volume = {5},
     year = {2008},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SEMR_2008_5_a19/}
}