. "The thermionic Valve and its developments in radio-telegraphy and telephony" . . . "The Thermionic valve and its developments in Radio-Telegraphy and Telephony"@en . . . . . . . . "Thermionic valve and its development in radio-telegraphy & telephony"@en . . . . . "Thermionic valve"@en . "The thermionic valve and its developments in radio-telegraphy and telephony"@en . "The thermionic Valve and its developments in radiotelegraphy and telephony" . "The thermionic valve and its developments in radio-telegraphy and telephony" . "The thermionic value and its developments in radiotelegraphy and telephony"@en . . "The thermionic valve and its developments in radiotelegraphy and telephony"@en . "The thermionic valve and its developments in radiotelegraphy and telephony" . . . "The Thermionic Valve"@en . . . . . . . . . "The Thermionic Valve, and its developments in Radio-telegraphy and Telephony"@en . . . . . . "The thermionic valve and its development in radio-telegraphy and telephony"@en . . . . "The thermionic valve" . "The thermionic valve"@en . . . . . . "Décharges électriques." . . "Télégraphie sans fil." . . "Telegraph, Wireless." . . . . "Radio." . . "Electric discharges." . .