@en|Scanning of a 1953 [[Sheaffer]] advertising for a [[Snorkel Pen]], ''Sentinel'' model. Retouched by the author for a better sharpness. Published on ''The National Geographic Magazine''. Date from copyright note. | @en|Scanning of a 1953 [[Sheaffer]] advertising for a [[Snorkel Pen]], ''Sentinel'' model. Retouched by the author for a better sharpness. Published on ''The National Geographic Magazine''. Date from copyright note. |