for sound recordings.PD-1923Public domain in the United States//commons.wikimedia.org/wiki/File:Good_English-_Book_Two_(IA_goodenglishbookt00elso).pdf...
sound recordings.PD-1923Public domain in the United States//commons.wikimedia.org/wiki/File:Good_English-_Book_Three_(IA_goodenglishbookt00elso_0).pdf...