@article{SM_2006_197_8_a4,
     author = {Yu. M. Dyukarev},
     title = {Deficiency numbers of symmetric operators generated
},
     journal = {Sbornik. Mathematics},
     pages = {1177--1203},
     publisher = {mathdoc},
     volume = {197},
     number = {8},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2006_197_8_a4/}
}