@article{UMJ_2017_3_1_a4,
     author = {Alexander L. Popovich},
     title = {Finite nilsemigroups with modular congruence lattices},
     journal = {Ural mathematical journal},
     pages = {52--67},
     year = {2017},
     volume = {3},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/UMJ_2017_3_1_a4/}
}