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\bibitem{Leroux_etal1999} {\textquotedblleft}\textit{A homologous series Pb$_{2n+1}$Nb$_{2n-1}$O$_{7n-1}$ studied by electron microscopy}{\textquotedblright}. Leroux C, Badeche T, Nihoul G, Richard O, Van Tendeloo G, European physical journal: applied physics \textbf{7}, 33 (1999).   http://doi.org/10.1051/epjap:1999196

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