@article{AL_1982_21_3_a0,
     author = {T. A. Martynova},
     title = {The largest groupoid of varieties of semigroups with zero},
     journal = {Algebra i logika},
     pages = {251--268},
     publisher = {mathdoc},
     volume = {21},
     number = {3},
     year = {1982},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1982_21_3_a0/}
}