1. I. Langwuir, J. Franklin Ist.,196, 59, 1923.
2. I. Langwuir, Gen. El. Review,26, 731, 1923.
3. I. Langmuir, H. Moth-Smith, Gen. El. Review,27, 449, 538, 616, 762, 810, 1924.
4. J. F. Waymouth, J. Appl. Phys.,30, 9, 1404, 1959.
5. W. Verweij, Probe Measurements and Determination of Electron Mobility in the Positive Column of Low-Pressure Mercury-Argon Discharges. Thesis, Utrecht, 1960.