@article{PDM_2021_4_a0,
     author = {D. V. Solomatin},
     title = {Researches of semigroups with planar {Cayley} graphs: results and problems},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {5--57},
     publisher = {mathdoc},
     number = {4},
     year = {2021},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2021_4_a0/}
}