00946nam0-22003011i-450-99000050895040332120080610141655.0000050895FED01000050895(Aleph)000050895FED0100005089520020821d1948----km-y0itay50------baenga-------001yyIonospheric radio propagationCentre radio propagation laboratoryWashingtonU. S. Governement printing office1948209 p.ill.26 cmnational bureau of standardscircular 462Propagazione onde radio ionosferiche621.384'11United StatesCentral radio propagation laboratory492048ITUNINARICAUNIMARCBK99000050895040332110 E III 21S.I.DINELDINELIonospheric radio propagation330724UNINA