ROAR
Open Access Repositories Register
DOAB (Directory of Open Access Books)
Free access to peer-reviewed open access academic books, helping users find reliable open access book publishers.
Eureka
Online catalogue of the European Council Library.
Biblioteca Digital da ONU
United Nations Digital Library.
MDPI – Multidisciplinary Digital Publishing Institute
Publisher of open access scientific journals. Publishes more than 390 peer-reviewed journals
Open Thesis
Theses with free access.
OpenDOAR – Directory of Open Access Repositories
Directory of Institutional Repositories. Includes 40 Portuguese Institutional Repositories.
Biblioteca e Arquivos da Comissão Europeia
Access to information on the policies, history and integration of the European Union (EU).
UNESDOC
Database of the United Nations Educational, Scientific and Cultural Organisation, including all its digital publications
Open Science Directory
Contains around 13,000 open access scientific periodicals