Open-access repository
freely accessible repository of research publications and data
Crystallography Open Database
Transporter Classification database
Biodiversity Heritage Library
Stanford Physics Information Retrieval System
Doria
Research Papers in Economics
Theseus
Lunar and Planetary Institute
Education Resources Information Center
HAL
DiVA
National Science Digital Library
BASE (Bielefeld Academic Search Engine)
Archaeology Data Service
e-LIS
Horizon Pleins textes
Astrophysics Data System
Social Science Research Network
University of Florida Digital Collections
Open Knowledge Repository
Library and Archives Canada
PANGAEA