@article{DMGT_2001_21_1_a1,
     author = {Havel, Ivan and Zelinka, Bohdan},
     title = {On 2-periodic graphs of a certain graph operator},
     journal = {Discussiones Mathematicae. Graph Theory},
     pages = {13--30},
     publisher = {mathdoc},
     volume = {21},
     number = {1},
     year = {2001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGT_2001_21_1_a1/}
}