Nowadays, challenging parameter-free studies within computational condensed-matter physics facilitate the rapid progress of semiconductor technology towards computer-aided materials design. Theoretical-spectroscopy techniques provide insight into electronic excitations, dealing with the many-body aspect arising due to the involved electron-electron interaction. In this work, such numerical approaches are further developed and applied to the transparent conductive oxides MgO, ZnO, and CdO. These materials are important for transparent-oxide electronics, e.g., photovoltaics. Electronic...