00309nam a22000977a 4500 621.381 USE'O THE USE OF ELECTRONIC VALVES PART-3 PHOTOCELLS TRANSMISSION HIH VALVES AND COLD CATHODE GAS FIELDS VALVES LONDON BRITISH STANDARD INTERNATIONAL 1956 15P BK 582963 582963 0 0 0 0 CEME CEME GEN 2017-06-12 0 621.381 USE'O CEME-9039 2021-06-28 2021-06-28 BK