Resumen: Constants of motion, Lagrangians and Hamiltonians admitted by a family of relevant nonlinear oscillators are derived using a geometric formalism. The theory of the Jacobi last multiplier allows us to find Lagrangian descriptions and constants of the motion. An application of the jet bundle formulation of symmetries of differential equations is presented in the second part of the paper. After a short review of the general formalism, the particular case of non-local symmetries is studied in detail by making use of an extended formalism. The theory is related to some results previously obtained by Krasil'shchi, Vinogradov and coworkers. Finally the existence of non-local symmetries for such two nonlinear oscillators is proved. Idioma: Inglés DOI: 10.1063/1.4922509 Año: 2015 Publicado en: JOURNAL OF MATHEMATICAL PHYSICS 56, 6 (2015), 063505 ISSN: 0022-2488 Factor impacto JCR: 1.234 (2015) Categ. JCR: PHYSICS, MATHEMATICAL rank: 25 / 53 = 0.472 (2015) - Q2 - T2 Factor impacto SCIMAGO: 0.792 - Statistical and Nonlinear Physics (Q2) - Mathematical Physics (Q2)