@article{ZNSL_2007_348_a5,
     author = {S. I. Repin},
     title = {Functional a posteriori estimates},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {147--164},
     year = {2007},
     volume = {348},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2007_348_a5/}
}