@article{GMJ_2003__10_3_51039,
     author = {Agranovich, M.S. and Amosov, B.A.},
     title = {On {Fourier} series in eigenfunctions of elliptic boundary value problems.},
     journal = {Georgian mathematical journal},
     pages = {401--410},
     year = {2003},
     volume = {10},
     number = {3},
     zbl = {1050.35054},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/GMJ_2003__10_3_51039/}
}