1. References for valve-voltmeters.
2. Bull, C. S. ‘The diode as an a.c. voltmeter’. J. Sci. Instrum. Oct. 1947.
3. Philips Tech. Rev., Jan. 1950. p. 206 gives details of the Philips GM 6006 voltmeter.
4. Amos, S. W. ‘Simple valve voltmeter’. Wireless World, 1950, 56, No. 12, 430 (Dec).
5. Waddington, D. E. O’N. ‘Silicon transistor multivoltmeter’. Wireless World, 1966, 72, No. 3, 111 (March).