@article{TM_1980_147_a3,
     author = {N. M. Ivochkina},
     title = {Second-order differential equations with $d$-elliptic operators},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {40--56},
     publisher = {mathdoc},
     volume = {147},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1980_147_a3/}
}