“The Approximate or Exact Analytical Solutions for the Differential Equations Which Describe Parametric Free Vibrations of Mechanical Systems”. 2013. Analele Universităţii "Dunărea de Jos" Din Galaţi. Fascicula XIV, Inginerie Mecanică = Annals of “Dunarea de Jos“ University of Galati. Fascicle XIV, Mechanical Engineering 20 (1): 65-68. https://ojs.ugal.ro/index.php/im/article/view/3556.