@article{AA_2002_14_3_a3,
     author = {I. S. Kats},
     title = {Linear relations generated by the canonical differential equation of dimension~2, and eigenfunction expansions},
     journal = {Algebra i analiz},
     pages = {86--120},
     publisher = {mathdoc},
     volume = {14},
     number = {3},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_2002_14_3_a3/}
}