Influence of oxygen vacancies on two-dimensional electron systems at SrTiO3-based interfaces and surfacesMichael Sing, Harald O. Jeschke, Frank Lechermann, Roser Valentí and Ralph ClaessenEur. Phys. J. Special Topics, 226 11 (2017) 2457-2475DOI: https://doi.org/10.1140/epjst/e2017-70059-7