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Publication of NL90200CpublicationCriticalpatent/NL90200C/xx
B43—WRITING OR DRAWING IMPLEMENTS; BUREAU ACCESSORIES
B43K—IMPLEMENTS FOR WRITING OR DRAWING
B43K24/00—Mechanisms for selecting, projecting, retracting or locking writing units
B43K24/02—Mechanisms for selecting, projecting, retracting or locking writing units for locking a single writing unit in only fully projected or retracted positions
B43K24/08—Mechanisms for selecting, projecting, retracting or locking writing units for locking a single writing unit in only fully projected or retracted positions operated by push-buttons
B43K24/088—Mechanisms for selecting, projecting, retracting or locking writing units for locking a single writing unit in only fully projected or retracted positions operated by push-buttons with spreading spring means