KELEVEDJIEV, P.; POPIVANOV, N. EXISTENCE OF SOLUTIONS OF BOUNDARY VALUE PROBLEMS FOR THE EQUATION $f(t,x,x’,x’’) = 0$ WITH FULLY NONLINEAR BOUNDARY CONDITIONS. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 94, p. 55–70, 2002. Disponível em: https://ftl5.uni-sofia.bg/index.php/fmi/article/view/190. Acesso em: 4 dec. 2024.