Migratory labor bills : hearings before the Subcommittee on Migratory Labor of the Committee on Labor and Public Welfare, United States Senate, Eighty-eighth Congress, first session, on S. 521, S. 522, S. 523, S. 524, S. 525, and S. 526, bills relating to various migratory labor programs, April 10, 23, and 24, 1963