Schema of the [[Omas 361]] double writing nib. Excerpt from original patent ({{Cite patent|US|2565667}}) first page. Retouched by the author for a better sharpness. | Schema of the [[Omas 361]] double writing nib. Excerpt from original patent ({{Cite patent|US|2565667}}) first page. Retouched by the author for a better sharpness. |