Open access to 700.000 bibliographical references of grey literature (paper) produced in Europe and allows you to export records and locate the documents - including technical or research reports, doctoral dissertations, conference papers, official publications, and other types of grey literature.
Cochrane Library of Systematic Reviews - high quality information to inform health decision-making
BioMed Central - open access journals in the field of bio-medical science
BioRxiv - print server for Biology
MedRxiv - pre-print server for health sciences