@article{SM_2018_209_6_a2,
     author = {A. K. Gushchin},
     title = {The {Luzin} area integral and the nontangential maximal function for solutions to a~second-order elliptic equation},
     journal = {Sbornik. Mathematics},
     pages = {823--839},
     publisher = {mathdoc},
     volume = {209},
     number = {6},
     year = {2018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2018_209_6_a2/}
}