Double taxation conventions, hearing, 85th Congress, 2d session, on supplementary income tax protocol with United Kingdom (ex. A. 85th Cong., 2d sess.), supplementary income tax convention with Belgium (ex. B 85th Cong., 2d sess.), and notification of extension of income tax convention with United Kingdom (ex. C, 85th Cong., 2d sess.), July 1, 1958.