Oxidation State of the Unusual Rare Earth (R= Ce, Pr and Tb) in Double-Layer High-Tc Superconductors U. Staub, L. Soderholm, S. Skanthakumar et M.R. Antonio J. Phys. IV France, 7 C2 (1997) C2-1077-C2-1079 DOI: 10.1051/jp4:19972141