000 00248nam a22001097a 4500
082 _a621.384 HAC'I
100 _aHALLOWS, R. W
_979918
245 _aINTRODUCTION TO VALVES
260 _aLONDON
_bWIRELESS WORLD
_c1953
300 _a152P
942 _cBK
999 _c584900
_d584900