"Radio Conference Recommendations: New Wave Lengths", Radio Age, May 1923, page 11. Beginning with these assignments radio stations ended the practice of broadcasting their market reports and weather forecasts on the separate 485 meter wavelength.
"New stations", Radio Service Bulletin, June 1, 1922, page 2. Limited Commercial license, serial #699, issued May 4, 1922 to the Detroit Free Press for operation on 360 and 485 meters for a three month period.
"New Stations", Radio Service Bulletin, September 1, 1925, page 3.
"Alterations and corrections", Radio Service Bulletin, September 1, 1925, page 7. There were only a small number of dual call sign stations during the 1920s and 1930s, usually resulting from station consolidations. Most remaining examples disappeared after May 15, 1933, when the Federal Radio Commission requested that stations drop call letters no longer in regular use. ("Double Call Letters Are Being Eliminated", Washington (D.C.) Evening Star, June 25, 1933, Part 4, page 6.)
"Alterations and corrections", Radio Service Bulletin, September 1, 1925, page 7. There were only a small number of dual call sign stations during the 1920s and 1930s, usually resulting from station consolidations. Most remaining examples disappeared after May 15, 1933, when the Federal Radio Commission requested that stations drop call letters no longer in regular use. ("Double Call Letters Are Being Eliminated", Washington (D.C.) Evening Star, June 25, 1933, Part 4, page 6.)
