Normal Extensions of an Singular Differential Operator for First Order
  In this work, in the Hilbert space of vector-functions L^2 (H,(-\infty,a)\cup(b,+\infty)),a<b all normal extensions of the minimal operator generated by linear singular formally normal differential expression l(\cdot)=(d/dt+A_1,d/dt+A_2) with a selfadjoint operator coefficients A_1 andA_2 in any Hilbert space H, are described in terms of boundary values. Later structure of the spectrum of these extensions is investigated. 
E.Bairamov and R.O.Mert and Z.I.Ismailov
math.FA