"Sunspots." . . "Bibliographies." . . "Electromagnetic radiation." . . "Radio interference." . . "Ionospheric propagation." . . "Periodic variations." . . . . . . . "The report is intended to provide only a brief description of auroral characteristics plus an index of pertinent literature."@en . . . . . . . "A REVIEW OF AURORAL CHARACTERISTICS"@en . . . . . . "Ionospheric disturbances." . . . . "THOMPSON RAMO WOOLDRIDGE INC LOS ANGELES CALIF." . . "Physical properties)" . . "(Atmospherics." . . "Magnetic storms." . . "(Aurorae." . . "Aurorae)" . "Wave propagation." . .