Substitution of into the homogeneous Euler-Cauchy equation gives , so . Use the solution that vanishes at zero and that decays at infinity. Their Wronskian is . The half-line Green function for the first cylindrical harmonic is therefore
It is continuous at , its first derivative has jump , and it solves the homogeneous equation elsewhere. Thus for integration with ordinary measure . The boundary conditions hold for each fixed .
Integrating against the forcing gives
Since the two integrals are and , respectively,
A Taylor expansion gives near zero, while at infinity. This verifies the two endpoint limits; direct differentiation verifies on . The differential expression itself is singular at zero, so the endpoint condition is imposed by continuity. No nonzero combination of and satisfies both homogeneous endpoint conditions, proving uniqueness.