?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aulast=Cassidy&rft.aufirst=DB&rft.au=Cassidy%2C+DB&rft.atitle=Experiments+with+a+high-density+positronium+gas&rft.volume=95&rft.date=4+November+2005&rft.issue=19&rft.title=Physical+Review+Letters&rft.issn=0031-9007&rft.genre=article