Thorium-dopinginduced superconductivity up to 56 K in GdThxFeAsOCao Wang, Linjun Li, Shun Chi, Zengwei Zhu, Zhi Ren, Yuke Li, Yuetao Wang, Xiao Lin, Yongkang Luo, Shuai Jiang, Xiangfan Xu, Guanghan Cao and Zhu'an XuEPL, 83 6 (2008) 67006DOI: https://doi.org/10.1209/0295-5075/83/67006