@article{CRMATH_2002__334_6_457_0,
     author = {Volpert, Vitaly and Volpert, Aizik},
     title = {Normal solvability of linear elliptic problems},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {457--462},
     publisher = {Elsevier},
     volume = {334},
     number = {6},
     year = {2002},
     doi = {10.1016/S1631-073X(02)02286-0},
     language = {en},
     url = {http://www.numdam.org/articles/10.1016/S1631-073X(02)02286-0/}
}