?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adissertation&rft.aulast=van+Reeth&rft.au=van+Reeth%2C+Peter+George&rft.aufirst=Peter+George&rft.date=1997&rft.tpages=200&rft.title=Theoretical+studies+of+positronium+formation+in+low+energy+positron-helium+collisions&rft.inst=UCL+(University+College+London)&rft.degree=Doctoral