@article{MZM_1976_19_6_a1,
     author = {P. Ya. Grushko},
     title = {Semiplane lattices over irreducible groups},
     journal = {Matemati\v{c}eskie zametki},
     pages = {833--842},
     publisher = {mathdoc},
     volume = {19},
     number = {6},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1976_19_6_a1/}
}