1. B. I. Shvetskii, Electronic Measuring Instruments with a Digital Display [in Russian], Izd. Tekhnika, Kiev (1964).
2. L. I. Volgin and V. V. Klanberg, “Converting Voltmeter V-23,” Advanced Scientific Research and Industrial Experience, No. 18-65-272/8, GOSINTI (1965).
3. P. Richman, IEEE Intern. Conv, Rec.,11, No. 5 (1963).
4. L. I. Volgin, Izv. vuz. priborostr.,7, No. 3 (1964).
5. L. I. Volgin, Transactions of the All-Union Scientific-Research Conference on Radioelectronic Methods for Measuring Electrical Voltages and Ohmic Resistances, Tallin (1965).