New: OpenURL resolver now requires login.
As of September 7, 2007 the OpenURL resolver will require users to have an account and to supply their login credentials in the 'pid' or 'req_dat' parameters.
Example:
http://www.crossref.org/openurl?url_ver=Z39.88-2004&rft_id=info:doi/10.1103/PhysRev.47.777&req_dat=username:password
http://www.crossref.org/openurl?pid=username:password&id=doi:10.1103/PhysRev.47.777
CrossRef members may use their system account. Others may click here to obtain an OpenURL account.
For further information please visit: http://www.crossref.org/openurl_info.html