?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adissertation&rft.au=Bell%2C+Sarah+Elizabeth&rft.aulast=Bell&rft.aufirst=Sarah+Elizabeth&rft.inst=UCL+(University+College+London)&rft.title=The+role+of+differentiation+antigens+in+T+cell+ontogeny+and+immune+function&rft.degree=Doctoral&rft.date=1991&rft.tpages=262