[Fan, Ai-Hua] Cent China Normal Univ, Sch Math & Stat, Wuhan 430079, Peoples R China.
[Fan, Ai-Hua] Univ Picardie Jules Verne, CNRS, LAMFA UMR 6140, F-80039 Amiens 1, France.
[Jordan, Thomas] Univ Bristol, Sch Math, Bristol BS8 1TW, Avon, England.
[Liao, Lingmin] Univ Paris Est Creteil, CNRS, LAMA UMR 8050, F-94010 Creteil, France.
[Rams, Michal] Polish Acad Sci, Inst Math, PL-00956 Warsaw, Poland.