1. “Lead-mercury-based superconductors – the 1212-cuprate Pb0.7Hg0.3Sr2+xCa0.7Nd0.3-xCu2O7- and the new oxycarbonate Pb0.7Hg0.3Sr4Cu2CO3O7”. Martin C, Hervieu M, Huvé M, Michel C, Maignan A, Van Tendeloo G, Raveau B, Physica: C : superconductivity 222, 19 (1994).   http://doi.org/10.1016/0921-4534(94)90109-0