@article{ISU_2013_13_4_a2,
     author = {D. A. Bredikhin},
     title = {On classes of groupoids of relations with diophantine operations},
     journal = {Izvestiya of Saratov University. Mathematics. Mechanics. Informatics},
     pages = {28--34},
     publisher = {mathdoc},
     volume = {13},
     number = {4},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ISU_2013_13_4_a2/}
}