@article{ZNSL_2003_295_a8,
     author = {R. G. Shterenberg},
     title = {Schr\"odinger operator in a~periodic waveguide on the plane and quasi-conformal mappings},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {204--243},
     year = {2003},
     volume = {295},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2003_295_a8/}
}