On fully discrete Galerkin methods of second-order temporal accuracy for the nonlinear Schrödinger equation. G.D. Akrivis; V.A. Dougalis; ... — 1991 Numerische Mathematik
An Approximation Theorem for Second-Order Evolution Equations. G.A., Dougalis, V.A., Serbin, S.M. Baker — 1980 Numerische Mathematik