@article{DAN_1990_311_5_a0,
     author = {A. N. Artyushin},
     title = {Variational inequalities for the wave equation with a constraint},
     journal = {Doklady Akademii Nauk},
     pages = {1033--1035},
     year = {1990},
     volume = {311},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1990_311_5_a0/}
}