In Paraguay, stamps were used on the packages to show that tax had been paid.
This is a stamp used around 1965 or 1970.
The text is 'REPUBLICA DEL PARAGUAY', 'IMPUESTO AL CONSUMO INTERNO',
and 'PRODUCCION EXTRANJERA'. The value is 30 Centimos.
The stamp was used for imported cards, and there is a wet stamp on it, probably
showing the importer.
(from a scan by José Luiz G. Pagliari)