To amend Section 2(b) of the Clayton Act : Hearings before the Subcommittee on Antitrust and Monopoly of the Committee on the Judiciary, United States Senate, Eighty-sixth Congress, first session pursuant to S. Res. 57, on S. 11, a bill to amend the Clayton Act, as amended, by the Robinson-Patman Act with reference to equality of opportunity, and S. 138, a bill to define the application of the Clayton and Federal Trade Commission Acts to certain pricing practices. (United States Government Printing Office, 1959)