| Contracting Parties/Signatories | Signature | Instrument | In Force | Details |
|---|---|---|---|---|
| Austria | January 4, 1960 | May 3, 1960 | ||
| Denmark | January 4, 1960 | May 3, 1960 | ||
| Iceland | Accession : December 4, 1969 | March 1, 1970 | ||
| Liechtenstein | January 4, 1960 | May 3, 1960 | ||
| Norway | January 4, 1960 | May 3, 1960 | ||
| Portugal | January 4, 1960 | May 3, 1960 | ||
| Sweden | January 4, 1960 | May 3, 1960 | ||
| Switzerland | January 4, 1960 | May 3, 1960 | ||
| United Kingdom | January 4, 1960 | May 3, 1960 |