Study groups 1, 12, 5, 6, 7 : questions of the CCIR, 1990: volume XV-1 / International Telecommunication Union.International Radio Consultative Committee
Commission d'études 1, 12, 5, 6, 7 : questions du CCIR, 1990: volume XV-1 / International Telecommunication Union
Study groups 10, 11, CMTT : questions of the CCIR, 1990: volume XV-3 / International Telecommunication Union
Commission d'études 4, 9 : questions du CCIR, 1990: volume XV-4 / International Telecommunication Union