2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/148845We show that closed, radiation-filled Friedmann-Robertson-Walker quantum universes of arbitrary factor ordering obey the Whittaker equation. We also present the formal Witten factorization as well as the double Darboux strictly isospectral scheme for the Whittaker equation6 pages, LaTexGeneral Relativity and Quantum Cosmologytext