This series is comprised of 39 titles and contains pamphlets, reprints, bibliograhical transcripts, brochures, exhibit catalogues, theses, books, charts, and congress protocols. The publications range in date from 1926 to 1951 (with greatest coverage in the 1930s) and are written in four different languages. They deal with questions of radio broadcasting, the main topics being educational broadcasting and the relation between radio and international understanding.