BRAYNOV, P.; CHRISTOV, O. Non-integrability of a Hamiltonian system, based on a problem of nonlinear vibration of an elastic string. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 99, p. 137–153, 2009. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/118. Acesso em: 4 dec. 2024.