@article{CMUC_2004__45_1_a1,
     author = {Song, Seok-Zun and Kang, Kyung-Tae and Yi, Sucheol},
     title = {Perimeter preservers of nonnegative integer matrices},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {9--15},
     publisher = {mathdoc},
     volume = {45},
     number = {1},
     year = {2004},
     mrnumber = {2076857},
     zbl = {1099.15001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_2004__45_1_a1/}
}