@article{DAN_1986_291_1_a15,
     author = {A. T. Il'ichev},
     title = {The {Sturm--Liouville} problem for stationary axisymmetric gravitational fields},
     journal = {Doklady Akademii Nauk},
     pages = {67--71},
     publisher = {mathdoc},
     volume = {291},
     number = {1},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1986_291_1_a15/}
}