The origin of orbital angular momentum quantum numbers from spherical harmonic solutions of the Schrödinger equation is a foundational principle of quantum mechanics and standard textbook knowledge that does not require citation.
The claim states a standard textbook fact of quantum mechanics regarding the separation of variables of the Schrödinger equation in spherical coordinates, where the angular portion yields the spherical harmonics and the associated quantum numbers (l and m). None of the retrieved papers specifically test or dispute this fundamental relationship as their primary finding, making it a foundational piece of common knowledge within physics.