2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/159484We introduce a method of approximate nonclassical Lie-Bäcklund symmetries for partial differential equations with a small parameter and discuss applications of this method to finding of approximate solutions both integrable and nonintegrable equations.Published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA/Mathematical PhysicsExactly Solvable and Integrable Systemstext