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\bibitem{Martin_etal1994} {\textquotedblleft}\textit{Lead-mercury based superconductors: the 1212 cuprate Pb$_{0.7}$Hg$_{0.3}$Sr$_{2+x}$Ca$_{0.7}$Nd$_{0.3-x}$Cu$_{2}$O$_{7-\delta}$ and the new oxycarbonate Pb$_{0.7}$Hg$_{0.3}$Sr$_{4}$Cu$_{2}$CO$_{3}$O$_{7}$}{\textquotedblright}. Martin C, Hervieu M, Huv{\'e} M, Michel C, Maignan A, Van Tendeloo G, Raveau B, Physica C-Superconductivity And Its Applications \textbf{222}, 19 (1994)

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