@article{ZNSL_1997_241_a1,
     author = {E. A. Hirsch},
     title = {Separating sings in the propositional satisfiability problem},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {30--71},
     year = {1997},
     volume = {241},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1997_241_a1/}
}