@article{SM_1994_79_2_a2,
     author = {V. V. Volchkov},
     title = {New theorems on the~mean for solutions of {the~Helmholtz} equation},
     journal = {Sbornik. Mathematics},
     pages = {281--286},
     publisher = {mathdoc},
     volume = {79},
     number = {2},
     year = {1994},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1994_79_2_a2/}
}