ELECTRONIC JOURNAL OF DIFFERENTIAL EQUATIONS, 2016 (SCI-Expanded)
Based on Calkin-Gorbachuk method, we describe all selfadjoint extensions of the minimal operator generated by linear multipoint singular symmetric differential-operator, as a direct sum of weighted Hilbert space of vector-functions. Another approach to the investigation of this problem has been done by Everitt, Zettl and Markus. Also we study the structure of spectrum of these extensions.