KLZ (English Wikipedia)

"Radio stations 40 or more years old in 1962" (KLZ entry), Broadcasting, May 14, 1962, page 124.
"1922--year radio's population soared" Broadcasting, May 14, 1962, page 88.
"KLZ Denver" Variety Radio Directory (1937-1938 edition), page 413. Establishment date for KLZ is listed as June 1920.
"Amateur Radio Stations Licensed During the Month of September, 1915", The Electrical Experimenter, February 1916, page 567. The "9" in 9WH's call sign indicated that the station was located in the 9th Radio Inspection district.
"Amateur Radio Stations: 9ZAF", QST, January 1923, pages 61-62.
"How Denver's Little Store Became Big", The Radio Dealer, January 1923, page 29.
"Broadcast Station Calls With a Past" by William Fenwick, Radio Broadcast, July 1928, page 150. The KLZ call had previously been assigned to a marine radio station aboard the Speedwell, which sank on September 29, 1920, in the Gulf of Mexico during a hurricane.
"Six stations being sold for nearly $15 million." Broadcasting - Telecasting, March 8, 1954, pp. 27-28.

broadcastprofessionals.org

Kreck, Dick. "Radio days recalled". The Denver Post. Retrieved August 3, 2022.

"Ninth District—Alphabetically by owners of stations", Amateur Radio Stations of the United States (June 30, 1920, edition), page 103.
"Ninth District—Alphabetically by call signals", Amateur Radio Stations of the United States (June 30, 1921, edition), page 191.
"New Stations: Special Land Stations", Radio Service Bulletin, August 1, 1921, page 3. The "Z" in 9ZAF's call sign indicated that the station held a Special Amateur license.
"Amendments to Regulations", Radio Service Bulletin, January 3, 1922, page 10.

"Radio Station KLZ Denver", Pikes Peak Radio & Electronics Museum (pikespeakradiomuseum.com)

"KLZ is a Real Radio in the Home" by Vera Brady Shipman, Radio in the Home magazine, February 1925, pages 29-30.

Roberts, Michael (March 19, 2007). "Games Over". Denver Westword. Retrieved July 4, 2012.