Exchange of notes between the government of the United Kingdom of Great Britain and Northern Ireland on their own behalf and on behalf of the government of the Federation of Rhodesia and Nyasaland and the government of the United States of America amending the agreement of the 18th of July, 1951, regarding the development of the Rhodesia Railways : London, September 30/October 21, 1954 (Cmd. (Great Britain. Parliament) ;, 1955)