"New Stations: Special Land Stations", Radio Service Bulletin, July 1, 1916, page 3. The leading "9" on 9ZP's call sign indicated that it was located in the ninth Radio Inspection district. "Z" was reserved for stations operating under Special Amateur (class 5) licenses.
"Amateur Radio Stations of the United States" (Supplementary List brought up-to-date from August Wireless Age), Wireless Age, September 1922, page 96. The fact that "C" fell in the range A-W indicated that 9CLS was a standard amateur license.
"New Stations"Radio Service Bulletin, August 31, 1927, page 3.
"'Mrs. Pierre,' at 74, Will Retire" by Dorothy Dancker, Sioux Falls (South Dakota) Argus-Leader (included in "Ida McNeil: A Real Public Servant" (extension of July 19, 1962 remarks of Senator Karl E. Mundt), Congressional Record–Appendix, pages A5544-A5545).
