Wu, TtTtWuTSUNG-TSONG WU2020-04-282020-04-2819610031-899Xhttps://scholars.lib.ntu.edu.tw/handle/123456789/487240Properties of Normal Thresholds in Perturbation Theoryjournal article10.1103/PhysRev.123.689WOS:A19611451C00050