Useful links

Ciência Aberta - http://www.ciencia-aberta.pt
DOAB Directory of Open Access Books - https://www.doabooks.org/
DOAJ Directory of Open Access Journals - https://doaj.org/
FOSTER - https://www.fosteropenscience.eu/
Networked Digital Library of Theses and Dissertations (NDLTD) - http://www.ndltd.org/
OpenAIRE Explore - https://explore.openaire.eu/search/find
OpenDOAR The Directory of Open Acces Repositories - http://www.opendoar.org/
PubMed - https://www.ncbi.nlm.nih.gov/pubmed
RCAAP - http://www.rcaap.pt
ROAR Registry of Open Access Repositories - http://roar.eprints.org/
Sherpa Romeo - https://v2.sherpa.ac.uk/romeo/
SPARC (the Scholarly Publishing and Academic Resources Coalition) - http://sparcopen.org/
UC Open Science - https://www.uc.pt/openscience
Zenodo - https://zenodo.org/