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\bibitem{Shi_etal1996} {\textquotedblleft}\textit{Electronic structure of a Si \delta-doped layer in a GaAs/Al$_{x}$Ga$_{1-x}$As/GaAs quantum barrier}{\textquotedblright}. Shi JM, Koenraad PM, van de Stadt AFW, Peeters FM, Devreese JT, Wolter JH, Physical Review B \textbf{54}, 7996 (1996).   http://doi.org/10.1103/PhysRevB.54.7996

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