@article{PDM_2018_3_a4,
     author = {N. A. Artemova},
     title = {Periods of $\varphi$-graphs},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {46--53},
     year = {2018},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2018_3_a4/}
}