| # | Country | Total Patents | |
|---|---|---|---|
| #1 | Switzerland | 12 | |
| #2 | Germany | 9 | |
| #3 | Austria | 7 | |
| #4 | United Kingdom | 3 | |
| #5 | Denmark | 2 | |
| #6 | Canada | 1 | |
| #7 | United States | 1 |
| # | Industry | |
|---|---|---|
| #1 | Control | |
| #2 | Consumer goods | |
| #3 | Audio-visual technology | |
| #4 | Textiles and paper | |
| #5 | Machines | |
| #6 | Furniture and games | |
| #7 | Optics |
| # | Technology | |
|---|---|---|
| #1 | Teaching materials | |
| #2 | Books | |
| #3 | Copy machines | |
| #4 | Special information storage | |
| #5 | Unspecified technologies | |
| #6 | Games | |
| #7 | Advertising | |
| #8 | Cameras |
| # | Name | Total Patents |
|---|---|---|
| #1 | Ritter Eduard | 20 |
| #2 | Eduard Ritter | 8 |
| #3 | Hans Poessl | 2 |
| #4 | Poessl Hans | 2 |
| #5 | Esch Paul Von | 1 |
| #6 | Von Esch Paul | 1 |
| Publication | Filing date | Title |
|---|---|---|
| CH611061A5 | Collection of problem sheets with solution check | |
| US3558142A | Recording tape magazine | |
| DE1254893B | Exercise sheet with solution control | |
| GB978697A | Checking device for correspondence courses | |
| GB839576A | Improvements in and relating to apparatus for the visual and aural presentation of information | |
| CA756812A | Didactic apparatus |