@article{ZNSL_1992_202_a6,
     author = {I. N. Ponomarenko},
     title = {On computation complexity problems concerning relation algebras},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {116--134},
     year = {1992},
     volume = {202},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1992_202_a6/}
}