Exportation of opium. [Part 1], December 11, 1920 : hearings before the Committee on Finance, United States Senate, Sixty-sixth Congress, third session on S. 4553, a bill to amend section 6 of an act approved January 17, 1914, entitled "An act to prohibit the importation and use of opium for other than medicinal purposes," approved February 9, 1909