@article{MZM_1995_57_6_a16,
     author = {I. A. Sheipak},
     title = {On~the basis properties of systems of root vectors of operators that are almost self-adjoint in {Pontryagin} spaces},
     journal = {Matemati\v{c}eskie zametki},
     pages = {937--940},
     publisher = {mathdoc},
     volume = {57},
     number = {6},
     year = {1995},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1995_57_6_a16/}
}