1872 Mahlon Loomis is granted the first patent for "wireless" communication. 1954 The first commercially marketed transistor radios appear (Regency TR-1).
1895 Guglielmo Marconi succeeds in signaling a distance of about 1.2 miles. 1938 Ailen invasion panic is spread by radio when Orson Wells broadcasts "War of the Worlds" 1941 Over eight million radios manufactured. 1942 Manufacture of home radio sets halted due to the war. 1957 Space Race starts when Russian satellite "Sputnik" sends radio "beep" back to earth.
1904 John Ambrose Fleming invents the first tube called The "Fleming Valve". 1926 The first AC (non battery) powered sets are marketed. Tube Radio Guides Crystal Radio Guides Transistor Radio Guides Boatanchors, Ham/SW Antennas History & Museums Radios For Sale/Wanted Radio Classifieds/Auctions Radio Forums/Message Boards Test Equipment Tube Tester Repair Services Tutorials/Training/Resources Antique Radio Clubs/Associations Radio Collector's Web Sites Manuals & Schematics Antique Radio Parts Vacuum Tubes Antique Radio Repair & Restoration Radio Workbenches Old Time Radio Shows AM Broadcast Transmitters Phonographs & Victrolas Annual Fests & Conventions Other Vintage Technology Suggest A Link Air Chief (Firestone) Air Chief Radios by Firestone Atwater Kent Atwater Kent Radios Atwater Kent Atwater Kent Information Bendix Radio The Bendix Radio Foundation Colby Colby Radio Research Laboratory, Auburn NY Crosley Jim's Antique Crosley Radio Page Curtis Mathes Glenn Waters's Vintage Curtis Mathes site De Forest Dr. 1906 (9 PM Christmas Eve) First Voice/Music Broadcast 1907 First Transatlantic Radio Service. Lee De Forest Radio Catalog Detrola Dennis and Bonnie Smith's Detrola Site International Radio (Kadettes) Info on Antique Kodel Radio John Leming's Kodel Radio History Midwest Mike Simpson's Midwest Radios Philco The Philco Repair Bench Philco Philco Radiola - RCA Radiola Radiobar Antique Wireless Association - AWA Historical Radio Society of Australia Canadian Vintage Radio Society - CVRS Radio Amateurs of Canada - RAC Radio Club Of America New Zealand Vintage Radio Society Norwegian Historical Radio Society Tube Collectors Association - TCA Vintage Radio and Phonograph Society Alabama Historical Radio Society Antique Radio Club of Illinois Arizona Antique Radio Club California Historical Radio Society - CHRS Southern California Antique Radio Society - SCARS Delaware Valley Historic Radio Club - DVHRC Florida Antique Wireless Group Heartland Antique Radio Association - HLARA Houston Vintage Radio Association - HVRA Indiana Historical Radio Society Jacksonville Antique Radio Society Michigan Antique Radio Club - MARC Mid-Atlantic Antique Radio Club Music City Vintage Radio Club Nashville TN New England Antique Radio Club - NEARC New Jersey Antique Radio Club Northland Antique Radio Club Minnesota Oklahoma Vintage Radio Collectors - OKVRC Ottawa Vintage Radio Club - OVRC Pittsburgh Antique Radio Society Schenectady NY Antique Radio Club Southeastern Antique Radio Society Vintage and Military Amateur Radio Society - V. 1909 First regular schedule of broadcasts from the Herrold College of Wireless and Engineering, San Jose, CA. 1915 Voice is first broadcast across the Atlantic ocean. Here's a quick list of books that I've found interesting or useful.
The list includes price guides, collector ("appreciation") books, history, and guides on repairing old radios and restoring wooden cabinets.
A caveat regarding collector guides: even the best ones don't (and can't) pretend to be complete.
And price information is always speculative, at best. And certain kinds of radios drift up or down in value as various fads grip the collector community.
In the end, a radio is worth only what somebody will hand you in cold, hard cash!
Your public library is another source of technical information.
Some of the most useful technical literature has been out of print for years, but may still be lurking in your library's shelves.