@en|Scanning of a 1954 [[Sheaffer]] advertising for a [[Snorkel Pen]], ''Sentinel'' version. Published on ''The National Geographic Magazine''. Retouched by the author for a better sharpness. Date from copyright note. | @en|Scanning of a 1954 [[Sheaffer]] advertising for a [[Snorkel Pen]], ''Sentinel'' version. Published on ''The National Geographic Magazine''. Retouched by the author for a better sharpness. Date from copyright note. |