Most of them were written by scholars at universities in China, including China Medical University, Sichuan University, Shandong University and Jiaotong University Medical School.
http://www.washingtonpost.com/news/morning-mix/wp/2015/03/27/fabricated-peer-reviews-prompt-scientific-journal-to-retract-43-papers-systematic-scheme-may-affect-other-journals/