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\bibitem{daCosta_etal2014} {\textquotedblleft}\textit{Geometry and edge effects on the energy levels of graphene quantum rings : a comparison between tight-binding and simplified Dirac models}{\textquotedblright}. da Costa DR, Chaves A, Zarenia M, Pereira JM, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics \textbf{89}, 075418 (2014).   http://doi.org/10.1103/PhysRevB.89.075418

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