@article{RM_1997_52_6_a24,
     author = {V. P. Serebryakov},
     title = {On the deficiency index of second-order matrix differential operators},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {1326--1327},
     publisher = {mathdoc},
     volume = {52},
     number = {6},
     year = {1997},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1997_52_6_a24/}
}