2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/120692We describe a method of obtaining closed-form complete solutions of certain second-order linear partial differential equations with more than two independent variables. This method generalizes the classical method of Laplace transformations of second-order hyperbolic equations in the plane and is based on an idea given by Ulisse Dini in 1902.11 pages, Plain LaTeX; Submitted to Proceedings of Waterloo Workshop on Computer Algebra devoted to the 60th birthday Of S.A.Abramov. The second version includes grant acknowledgements and minor changes in a couple of placesSymbolic ComputationExactly Solvable and Integrable SystemsF.2.2text