![German postage stamps used in this study. From left to right and top to... | Download Scientific Diagram German postage stamps used in this study. From left to right and top to... | Download Scientific Diagram](https://www.researchgate.net/publication/323268040/figure/fig1/AS:602315392290816@1520614588124/German-postage-stamps-used-in-this-study-From-left-to-right-and-top-to-bottom-S1-S2.png)
German postage stamps used in this study. From left to right and top to... | Download Scientific Diagram
German postage stamps used in this study. From left to right and top to... | Download Scientific Diagram
![Postage stamp from the Federal Republic of Germany in the German buildings from twelve centuries, large size series issued in 1967 Stock Photo - Alamy Postage stamp from the Federal Republic of Germany in the German buildings from twelve centuries, large size series issued in 1967 Stock Photo - Alamy](https://c8.alamy.com/comp/T6ER41/postage-stamp-from-the-federal-republic-of-germany-in-the-german-buildings-from-twelve-centuries-large-size-series-issued-in-1967-T6ER41.jpg)
Postage stamp from the Federal Republic of Germany in the German buildings from twelve centuries, large size series issued in 1967 Stock Photo - Alamy
![East German postage stamp commemorating science and socialism - Science History Institute Digital Collections East German postage stamp commemorating science and socialism - Science History Institute Digital Collections](https://scihist-digicoll-production-derivatives.s3.amazonaws.com/28f03bb7-a6ad-4f0f-8c89-0901311a7e4b/thumb_large/06944df3e653ed06eb6223c6d795c15e.jpg)