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Publication of NL23840CpublicationCriticalpatent/NL23840C/xx
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