| # | Country | Total Patents | |
|---|---|---|---|
| #1 | Sweden | 3 | |
| #2 | Germany | 2 | |
| #3 | Denmark | 2 | |
| #4 | Canada | 1 | |
| #5 | Switzerland | 1 | |
| #6 | Finland | 1 | |
| #7 | Norway | 1 | |
| #8 | United States | 1 |
| # | Industry | |
|---|---|---|
| #1 | Civil engineering |
| # | Technology | |
|---|---|---|
| #1 | Ladders | |
| #2 | Structural elements |
| # | Name | Total Patents |
|---|---|---|
| #1 | Engvall Erik Arne | 4 |
| #2 | Ritscher Thomas | 4 |
| #3 | Engvall Arne | 2 |
| #4 | Engvall E | 2 |
| #5 | Engvall A | 2 |
| #6 | Persson E | 1 |
| #7 | Keijser G | 1 |
| #8 | Keijser Georg | 1 |
| #9 | Georg Keijser | 1 |
| #10 | Arne Engvall | 1 |
| Publication | Filing date | Title |
|---|---|---|
| CA986678A | Strut construction | |
| DE1900643A1 | Construction and manufacturing process of a ladder |