@article{DAN_1967_173_4_a7,
     author = {I. S. Iokhvidov},
     title = {Unitary extensions of isometric operators in the {Pontrjagin} space $\Pi_1$ and continuations in the $\mathfrak{P}_1$ 
},
     journal = {Doklady Akademii Nauk},
     pages = {758--761},
     publisher = {mathdoc},
     volume = {173},
     number = {4},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_173_4_a7/}
}