2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/87353We show how the pre-exponential factor of the Feynman propagator for the harmonic oscillator can be computed by the generalized $ζ$-function method. Besides, we establish a direct equivalence between this method and Schwinger's propertime method.12 latex pages, no figuresPhysics Educationtext