  We consider symmetric second-order differential operators with real
coefficients such that the corresponding differential equation is in the limit
circle case at infinity. Our goal is to construct the theory of self-adjoint
realizations of such operators by an analogy with the case of Jacobi operators.
We introduce a new object, the quasiresolvent of the maximal operator, and use
it to obtain a very explicit formula for the resolvents of all self-adjoint
realizations. In particular, this yields a simple representation for the
Cauchy-Stieltjes transforms of the spectral measures playing the role of the
classical Nevanlinna formula in the theory of Jacobi operators.
