@article{ZNSL_1971_20_a15,
     author = {V. P. Orevkov},
     title = {On biconjunctive reduction classes},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {170--174},
     publisher = {mathdoc},
     volume = {20},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1971_20_a15/}
}