The Early Years of Radio | http://www.pbs.org/wgbh/aso/tryit/radio/earlyyears.html

KDKA begins to broadcast 1920 | http://www.pbs.org/wgbh/aso/databank/entries/dt20ra.html

KDKA, First Commercial Radio Station | http://ethw.org/KDKA,_First_Commercial_Radio_Station

An assortment of highlights about early U.S. radio history. http://earlyradiohistory.us/index.html

David Sarnoff, RCA, and the Development of Broadcast Entertainment http://bnrg.eecs.berkeley.edu/~randy/Courses/CS39C.S97/broadcast/broadcast.html

The National Capital Radio & Television Museum Bowie, Maryland http://ncrtv.org/

Radio and television communication by Lindsley, Charles Frederick , Published 1952 , Topics Radio broadcasting, Television broadcasting | https://archive.org/details/radiotelevisionc00lind