Pernal, K., Gidopoulos, N. I., & Pastorczak, E. (2015). Chapter Eleven - Excitation Energies of Molecules from Ensemble Density Functional Theory: Multiconfiguration Approaches. In P. E. Hoggan, & T. Ozdogan (Eds.), Electron correlation in molecules – ab initio beyond Gaussian quantum chemistry (199-229). Elsevier. https://doi.org/10.1016/bs.aiq.2015.06.001