local pride; all are sold and valid in Portugal. About 5-10 are issued each year, generally with themes relating to the Azores. References Notes Sources AskPhil – Glossary of Stamp Collecting Terms Encyclopaedia of Postal History Further reading Ferreira, Manuel. Os Correios Nos Açores: datas, selos, e postais. Ribeira Chã: Centro Paroquial, 1997 365p. Philately of the Azores