@article{TIMM_2012_18_3_a30,
     author = {V. Yu. Shaprynskii},
     title = {The periodicity of special elements in the lattice of semigroup varieties},
     journal = {Trudy Instituta matematiki i mehaniki},
     pages = {282--286},
     year = {2012},
     volume = {18},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TIMM_2012_18_3_a30/}
}