Investigation of improper activities in labor or management field, hearings, 85th Congress, 2d session, and 86th Congress, 1st session, pursuant to Senate resolutions 74 and 221, 85th Congress, and Senate resolution 44, 86th Congress. pt. 47. [Coin-operated amusement and vending machine industry], Feb. 26, 1958-Mar. 10, 1959.