2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89212A unified treatment is developed for the XXX-Heisenberg model and a long-ranged interaction model (the $H_2$ in Haldane-Shastry model) from the point of view of shift operators (or raising and lowering operators), based on which the energy spectra of the spin-chain models are determined. Some physical discussions are also made.26 pages, Latex file, Submitted to J. Phys. AQuantum Physicstext