Further Reading/ References:

1. Society of Telegraph Engineers. (1955) Thermionic valves, 1904‐1954: the first fifty years. London, The Institution of Electrical Engineers.
2. Okamura S. ed. (1994) History of Electron Tubes. Tokyo, Ohmsha.
3. Stokes, J. (1982) 70 Years of Radio Tubes and Valves. New York, Vestal Press.
4. Bowers, B. (2004) A century of electronics. IEE Review. 50 (11), 36-39: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1395384&isnumber=30357&tag=1
5. Redhead, P.A. (1998) The birth of electronics: Thermionic emission and vacuum. J. Vac. Sci. Technol. A16 (3), 1394-1401. http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JVTAD6000016000003001394000001&idtype=cvips&prog=normal