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Publication of FR666475ApublicationCriticalpatent/FR666475A/en
H01K9/00—Lamps having two or more incandescent bodies separately heated
H01K9/02—Lamps having two or more incandescent bodies separately heated to provide substitution in the event of failure of one of the bodies
H01K9/04—Lamps having two or more incandescent bodies separately heated to provide substitution in the event of failure of one of the bodies with built-in manually operated switch
FR666475D1928-10-161928-12-28
Improvements to incandescent electric lamps
ExpiredFR666475A
(en)