@article{ZNSL_1976_58_a16,
     author = {S. G. Mikhlin},
     title = {Variation-difference approximation},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {155--156},
     publisher = {mathdoc},
     volume = {58},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1976_58_a16/}
}