BEURTHERET, Charles. Progrès récent dans la constitution externe des tubes de puissance: le vapotron. 1954.

Offprint extracted of the "Bulletin de la Société française des électriciens", 7th series, Volume IV, No. 37, January 1954.
Only one another copy is known at the London British Library.

Charles Beurtheret (1909-1977) was chief engineer at the CFTH (Compagnie Française Thomson Houston, now Thalès).