Here are two .PDF files. The first dates to 1916 and was published in the General Electric Review. This technical article describes the various types of hot cathode gas-filled rectifiers and the development of the Tungar Rectifier. The title of the paper is The Hot Cathode Argon Gas Filled Rectifier, the file has been prepared and donated by Stig Comstedt. The second file also from General Electric is a brochure dating to 1945 reviewing the history of the Tungar rectifier and listing the then available types with short-form data on each. The image below is of the cover of the brochure (click to open).