@article{TM_1981_158_a16,
     author = {A. N. Tikhonov},
     title = {Approximate functional equations of the first kind},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {197--202},
     publisher = {mathdoc},
     volume = {158},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1981_158_a16/}
}