na INLIS000000000037161 Eng 0010-0324022116 Conference on tropospheric wave propagation London: Institution of Electrical Engineers, c1968 London: Institution of Electrical Engineers, c1968 vii, 251 hal. : ilus. ; 30 cm. vii, 251 hal. : ilus. ; 30 cm. R 621.381 31 Con c R 621.381 31 Con c Tropospheric radio wave propagation 3100087011795