@article{10_37236_1732,
     author = {A. Czygrinow and B. Nagle},
     title = {Matrix-free proof of a regularity characterization},
     journal = {The electronic journal of combinatorics},
     year = {2003},
     volume = {10},
     doi = {10.37236/1732},
     zbl = {1031.05070},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/1732/}
}