@article{CMFD_2021_67_2_a2,
     author = {V. Budyka and M. Malamud and K. Mirzoev},
     title = {Deficiency indices of block {Jacobi} matrices: survey},
     journal = {Contemporary Mathematics. Fundamental Directions},
     pages = {237--254},
     publisher = {mathdoc},
     volume = {67},
     number = {2},
     year = {2021},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/CMFD_2021_67_2_a2/}
}