@article{MZM_1998_63_1_a14,
     author = {V. G. Zvyagin},
     title = {The set of critical values of a potential {Fredholm} functional},
     journal = {Matemati\v{c}eskie zametki},
     pages = {133--135},
     publisher = {mathdoc},
     volume = {63},
     number = {1},
     year = {1998},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1998_63_1_a14/}
}