| Country | Action | Action Date | Effective Date |
|---|---|---|---|
| AUSTRIA | Signature | 22/12/1958 | |
| BELGIUM | Signature | 22/12/1958 | |
| DENMARK | Signature | 22/12/1958 | |
| FINLAND | Signature | 22/12/1958 | |
| GERMANY FEDERAL REPUBLIC | Signature | 22/12/1958 | |
| ITALY | Signature | 22/12/1958 | |
| LUXEMBOURG | Signature | 22/12/1958 | |
| NETHERLANDS THE | Signature | 22/12/1958 | |
| NORWAY | Signature | 22/12/1958 | |
| PORTUGAL | Signature | 22/12/1958 | |
| SWEDEN | Signature | 22/12/1958 | |
| SWITZERLAND | Signature | 22/12/1958 | |
| UNITED KINGDOM | Signature | 22/12/1958 |