... North-Holland, Amsterdam, The Netherlands, 1981 a 26 C Fabry and P Habets, Upper and lower solutions for second-order boundary value problems with nonlinear boundary conditions,” Nonlinear Analysis: Theory, ... Coster and P Habets, The lower and upper solutions method for boundary value problems,” in Handbook of Differential Equations, pp 69–160, Elsevier/North-Holland, Amsterdam, The Netherlands, 2004 ... C De Coster and P Habets, An overview of the method of lower and upper solutions for ODEs,” in Nonlinear Analysis and Its Applications to Differential Equations, vol 43 of Progr Nonlinear Differential...