@en|Scanning of a September 1930 [[Parker]] advertising for the [[Duofold]] model and its ''conversion'' to a desk pen. Published on ''The National Geographic'', Vol. LVIII, n.3. Retouched by the author for a better sharpness. Date on the cover. | @en|Scanning of a September 1930 [[Parker]] advertising for the [[Duofold]] model and its ''conversion'' to a desk pen. Published on ''The National Geographic'', Vol. LVIII, n.3. Retouched by the author for a better sharpness. Date on the cover. |