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Patent:GB131823
| Patent: | GB 131823 |
| Title: | Differentiating Calculators |
| Date: | 30.01.1919 |
| Place: | |
| Country: | Great Britain |
| Person: | Bogaert, J. P. van |
| Company: | |
| Internal Links: | |
| Keywords: | |
| Link to the patent office: (without guarantee) |  GB131823 |
Aus der Patentschrift GB131823