@article{RM_2006_61_2_a0,
     author = {S. M. Dudakov and M. A. Taitslin},
     title = {Collapse results for query languages in database theory},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {195--253},
     publisher = {mathdoc},
     volume = {61},
     number = {2},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_2006_61_2_a0/}
}