2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/53970A bibliography on the Hurwitz transformations is given. We deal here, with some details, with two particular Hurwitz transformations, viz, the $\grq \to \grt$ Kustaanheimo-Stiefel transformation and its $\grh \to \grc$ compact extension. These transformations are derived in the context of Fock-Bargmann-Schwinger calculus with special emphasis on angular momentum theory.30 pages, Tex, LYCEN 9110High Energy Physics - Theorytext