?url_ver=Z39.88-2004&rft_id=10.1073%2Fpnas.1323422111&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.au=Ingraffea%2C+Anthony+R.&rft.aulast=Ingraffea&rft.aufirst=Anthony+R.&rft.issue=30&rft.volume=111&rft.date=29+July+2014&rft.issn=1091-6490&rft.atitle=Assessment+and+risk+analysis+of+casing+and+cement+impairment+in+oil+and+gas+wells+in+Pennsylvania%2C+2000%E2%80%932012&rft.title=PNAS&rft.pages=10955-10960&rft.genre=article