%0 Generic %T Are our nation's ports secure? examining the Transportation Worker Identification Credential program : hearing before the Committee on Commerce, Science, and Transportation, United States Senate, One Hundred Twelfth Congress, first session, May 10, 2011. %U http://purl.fdlp.gov/GPO/gpo17293 %U http://purl.fdlp.gov/GPO/gpo17294