@article{SM_1998_189_4_a1,
     author = {R. R. Gadyl'shin and A. M. Il'in},
     title = {Asymptotic behaviour of the~eigenvalues of {the~Dirichlet} problem in a~domain with a~narrow slit},
     journal = {Sbornik. Mathematics},
     pages = {503--526},
     year = {1998},
     volume = {189},
     number = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1998_189_4_a1/}
}