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\bibitem{Singh_etal2013} {\textquotedblleft}\textit{Melting of graphene clusters}{\textquotedblright}. Singh SK, Neek-Amal M, Peeters FM, Physical review : B : condensed matter and materials physics \textbf{87}, 134103 (2013).   http://doi.org/10.1103/PhysRevB.87.134103

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