DIN 44402-14:1971-10 Measurements of electrical properties of electronic tubes; methods of measurement of emission current from hot cathodes for high-vacuum electronic tubes and valves
1971DIN 44402-14:1971-10 Measurements of electrical properties of electronic tubes; methods of measurement of emission current from hot cathodes for high-vacuum electronic tubes and valves
1971DIN 44402-14:1971 Measurements of electrical properties of electronic tubes; methods of measurement of emission current from hot cathodes for high-vacuum electronic tubes and valves