Emissora de ràdio (Catalan Wikipedia)

Halper, Donna L. John Shepard's FM Stations—America's first FM network." Boston Radio Archives (Bostonradio.org).
«The Yankee Network in 1936». The Archives @ Bostonradio.org. [Consulta: August 10, 2019].

bravehost.com

«Types of Technology, FM vs AM». kwarner.bravehost.com, July 13, 2012. Arxivat de l'original el July 13, 2012. [Consulta: August 10, 2019].

Guarnieri, M. «The age of vacuum tubes: Early devices and the rise of radio communications». IEEE Ind. Electron. M., 2012, pàg. 41–43. DOI: 10.1109/MIE.2012.2182822.
Guarnieri, M. «The age of vacuum tubes: the conquest of analog communications». IEEE Ind. Electron. M., 2012, pàg. 52-54. DOI: 10.1109/MIE.2012.2193274.
Baudino, Joseph E «Broadcasting's Oldest Stations: An Examination of Four Claimants». Journal of Broadcasting, vol. 21, Winter 1977, pàg. 61–82. DOI: 10.1080/08838157709363817.
Craig, Steve «How America Adopted Radio: Demographic Differences in Set Ownership Reported in the 1930–1950 O.S. Censuses». Journal of Broadcasting & Electronic Mitjana. Routledge, vol. 48, 2, 2004, pàg. 179–195. DOI: 10.1207/s15506878jobem4802_2.

«US841387A - Device for amplifying feeble electrical currents.». Google Patents, October 25, 1906. [Consulta: August 10, 2019].^{[Enllaç no actiu]}
«US879532A - Space telegraphy.». Google Patents, January 29, 1907. [Consulta: August 10, 2019].^{[Enllaç no actiu]}

Schmidt, Hans-Thomas. «Die Liebenröhre» (en alemany). Umleitung zur Homepage von H.-T. Schmidt. [Consulta: August 10, 2019]. DRP 179807

«Making the Modern World - Mass consumption». webarchive.nationalarchives.gov.uk. Arxivat de l'original el d’abril 5, 2017. [Consulta: de novembre 18, 2021].

«Making the Modern World - Mass consumption». webarchive.nationalarchives.gov.uk. Arxivat de l'original el d’abril 5, 2017. [Consulta: de novembre 18, 2021].

Atgelt, Carlos A. "Early History of Radio Broadcasting in Argentina." The Broadcast Archive (Oldradio.com).

Fessenden — The Next Chapter Rwonline.com Arxivat September 16, 2009, a Wayback Machine.

«FM Broadcasting Chronology». Jeff Miller Pages, June 23, 2017. [Consulta: August 10, 2019].

Fessenden — The Next Chapter Rwonline.com Arxivat September 16, 2009, a Wayback Machine.
«Types of Technology, FM vs AM». kwarner.bravehost.com, July 13, 2012. Arxivat de l'original el July 13, 2012. [Consulta: August 10, 2019].