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Because broadcasting requires use of the airwaves for the transmission of its signals, and because the airwaves can carry only a limited number of signals, it soon became apparent that some form of regulation was necessary. In 1927, the Radio Act (47 U.S.C.A § 81 et seq.) became law and the Federal Radio Commission (FRC) was created to police the broadcasting industry
If you have set bookmarks for different pages, then you can use this method to separate PDF files by top-level bookmarks. If you have not added any bookmark for your PDF file yet, you can also refer to this article about how to add bookmarks to PDF
The radio broadcasting of music and talk intended to reach a dispersed audience started experimentally around 1905–1906, and commercially around 1920 to 1923. The Wikipedia Telefon Hírmondó page includes a 1907 program guide which looks remarkably similar to the types of schedules used by many broadcasting stations some 20 or 30 years later