Considerations on the nonlinearity grade of the nonlinear mechanical elastic systems. (2012). Analele Universităţii "Dunărea de Jos" din Galaţi. Fascicula XIV, Inginerie mecanică = Annals of “Dunarea de Jos“ University of Galati. Fascicle XIV, Mechanical Engineering, 19(1), 13-18. https://ojs.ugal.ro/index.php/im/article/view/3680