SYMMETRIES OF THE HERGLOTZ VARIATIONAL PRINCIPLE IN THE CASE OF ONE INDEPENDENT VARIABLE. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 100, p. 113–122, 2011. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/249. Acesso em: 14 dec. 2025.