Nonlinear elliptic partial difference equations on graphs. Neuberger, John M. — 2006 Experimental Mathematics
A minimax principle, index of the critical point, and existence of sign-changing solutions to elliptic boundary value problems. Castro, Alfonso; Cossio, Jorge; Neuberger, John M. — 1998 Electronic Journal of Differential Equations (EJDE) [electronic only]
A sign-changing solution for a superlinear Dirichlet problem. II. Castro, Alfonso; Drábek, Pavel; Neuberger, John M. — 2003 Electronic Journal of Differential Equations (EJDE) [electronic only]