2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/36431We develop a method for constructing asymptotic solutions of finite-difference equations and implement it to a relativistic Schroedinger equation which describes motion of a selfgravitating spherically symmetric dust shell. Exact mass spectrum of black hole formed due to the collapse of the shell is determined from the analysis of asymptotic solutions of the equation.16 pages, 1 figureGeneral Relativity and Quantum Cosmologytext