Wong, G.-G.G.-G.WongWEI-SHU HOU et al.2019-12-272019-12-271992https://scholars.lib.ntu.edu.tw/handle/123456789/442850journal article10.1103/PhysRevD.50.R29622-s2.0-0000032682https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000032682&doi=10.1103%2fPhysRevD.50.R2962&partnerID=40&md5=e8a25d45ed7a6f40a271a1bc8209d33c