@article{SM_2006_197_4_a2,
     author = {I. N. Dolgikh and K. A. Mirzoev},
     title = {Deficiency indices and spectrum of self-adjoint extensions of some classes of differential operators},
     journal = {Sbornik. Mathematics},
     pages = {525--546},
     year = {2006},
     volume = {197},
     number = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2006_197_4_a2/}
}