|Note_en=Advertising for the [[Duofold]] models in [[celluloid]] (called [[Permanite]]), citing also the combination with the ''Duette'' pencil, called ''Duofold Duette''. | |Note_en=Advertising for the [[Duofold]] models in [[celluloid]] (called [[Permanite]]), citing also the combination with the ''Duette'' pencil, called ''Duofold Duette''. |