Elena Celledoni David Cohen Brynjulf Owren Symmetric Exponential Integrators with an Application to the Cubic Schrödinger Equation. 303-317 2008 8 Foundations of Computational Mathematics 3 http://dx.doi.org/10.1007/s10208-007-9016-7 db/journals/focm/focm8.html#CelledoniCO08