Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority to CH817664ApriorityCriticalpatent/CH431683A/de
Application filedfiledCritical
Priority to NL6407775Aprioritypatent/NL6407775A/xx
Priority to BE652032Dprioritypatent/BE652032A/fr
Publication of NL6407775ApublicationCriticalpatent/NL6407775A/xx