Treaties and other international acts series. 4280. Double taxation, taxes on income, supplementary convention between United States and Belgium, modifying convention of Oct. 28, 1948, as modified by supplementary convention of Sept. 9, 1952, signed Washington Aug. 22, 1957 [entered into force July 10, 1959], with exchange of notes signed Washington Apr. 2, 1954, and July 28, 1959.