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\bibitem{Varley_etal2011} {\textquotedblleft}\textit{Hydrogenated cation vacancies in semiconducting oxides}{\textquotedblright}. Varley JB, Peelaers H, Janotti A, van de Walle CG, Journal of physics : condensed matter \textbf{23}, 334212 (2011).   http://doi.org/10.1088/0953-8984/23/33/334212

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