@article{AA_1996_8_2_a6,
     author = {W. Lay and A. Ya. Kazakov and S. Yu. Slavyanov},
     title = {Eigenvalue problems for equations of the {Heun} class},
     journal = {Algebra i analiz},
     pages = {129--141},
     publisher = {mathdoc},
     volume = {8},
     number = {2},
     year = {1996},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_1996_8_2_a6/}
}