@article{MZ_1978__159_172656,
     author = {Earl A. Coddington and S.V. de Snoo},
     title = {Positive {Selfadjoint} {Extensions} of {Positive} {Symmetric} {Subspace.}},
     journal = {Mathematische Zeitschrift},
     pages = {203--214},
     year = {1978},
     volume = {159},
     zbl = {0358.47015},
     url = {http://geodesic.mathdoc.fr/item/MZ_1978__159_172656/}
}