Calculatrice Ancienne

Je cherche des infos sur cette calculatrice. D'un côté (jaune) on peut faire des additions
et de l'autre des soustractions. Tout cela avec retenues. Il y a écrit dessus : "Breveté S.G.D.G." et la marque est "ELPé"

J'ai trouvé la photo suivante :

---

Et Bas Vijfwinkel m'a donné les infos suivantes : The calculators are made in Germany but I don't know how old my calculator is.
They were made by ADDIATOR-rekenmachinefabriek C. Kubler, Berlin-Charlottenbrug 4, Leibnitzstr.33
For more information see the website :
Site à voir
The one I have is called 'Maximator-S'. It can perform additions on one side and substractions on the other side.
The text on my calculator is English. Is is fitted in a very heavy metal holder.
Behind the calculator a small version is fitted, which can be used a 'memory' or a second calculator for addition only.
The text on the second calculator is in German.
The manual also mentions a calculator which can multiply and divide. I have never seen that one.

---