@article{DAN_1980_253_2_a13,
     author = {A. N. Tikhonov},
     title = {On a reciprocity principle},
     journal = {Doklady Akademii Nauk},
     pages = {305--308},
     publisher = {mathdoc},
     volume = {253},
     number = {2},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1980_253_2_a13/}
}