@article{MMO_1974_31_a4,
     author = {V. A. Kondrat'ev and S. D. \`Eǐdel'man},
     title = {Positive solutions of linear partial differential equations},
     journal = {Trudy Moskovskogo matemati\v{c}eskogo ob\^{s}estva},
     pages = {85--146},
     publisher = {mathdoc},
     volume = {31},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MMO_1974_31_a4/}
}