@article{DE_2001_37_2_a12,
     author = {K. M. Medvedev},
     title = {The {Inverses} of {Solvable} {Extensions} and {Proper} {Restrictions} of the {Operation}  $-\operatorname{div}\operatorname{grad}$ {Are} {Not} {Volterra} {Operators}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {242--251},
     publisher = {mathdoc},
     volume = {37},
     number = {2},
     year = {2001},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2001_37_2_a12/}
}