@article{ZNSL_2003_305_a7,
     author = {L. N. Erofeeva},
     title = {On a~class of groupoids},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {136--143},
     publisher = {mathdoc},
     volume = {305},
     year = {2003},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2003_305_a7/}
}