Content Provider
Unknown
189
Directory of Open Access Journals: DOAJ Articles
94
DataCite Metadata Store (German National Library of Science and Technology)
56
Copernicus Publications: E-Journals
55
Defense Technical Information Center: DTIC Technical Reports database
42
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe)
41
Niedersächsisches Online-Archiv NOA
39
Cambridge University Press
37
LeibnizOpen (The Leibniz Association)
37
CERN Document Server (CDS)
31
Université de Nantes: HAL-UNIV-NANTES
29
Cambridge University Press (via Crossref)
27
University of California: eScholarship
25
Natural Environment Research Council: NERC Open Research Archive
23
University of Canterbury, Christchurch: UC Research Repository
23
DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB)
21
Ohio State University (OSU): Knowledge Bank
21
DESY Publication Database (PUBDB)
19
National Institute of Polar Research Repository, Japan
17
UNSW Sydney (The University of New South Wales): UNSWorks
16
Biodiversity Heritage Library (BHL)
15
OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research)
14
University of Michigan: Digital Collections
13
Institut national des sciences de l'Univers: HAL-INSU
12
Ghent University Academic Bibliography
10
PubMed Central (PMC)
10
Earth-Prints (Istituto Nazionale di Geofisica e Vulcanologia)
9
KITopen (Karlsruhe Institute of Technologie)
9
Springer Nature (via Crossref)
9
The University of Adelaide: Digital Library
9
eCite UTAS (University of Tasmania)
9
Caltech Authors (California Institute of Technology)
8
Hathi Trust Digital Library
8
University of Tasmania: UTas ePrints
8
Wiley Online Library (via Crossref)
8
MDPI Open Access Publishing
7
Padua Research Archive (IRIS - Università degli Studi di Padova)
7
Royal Holloway University of London: Royal Holloway Digital Repository
7
BORIS (Bern Open Repository and Information System, University of Bern)
6
ORA - Oxford University Research Archive
6
PANGAEA - Data Publisher for Earth & Environmental Science
6
SAGE Publications (via Crossref)
6
University of Wisconsin, Milwaukee: UWM Libraries Digital Collections
6
Uppsala University: Publications (DiVA)
6
HighWire Press (Stanford University)
5
PUMAlab (ISTI CNR - National Research Council)
5
University College London: UCL Discovery
5
University of Western Sydney (UWS): Research Direct
5
White Rose Research Online (Universities of Leeds, Sheffield & York)
5
WikiBooks - Open-content textbooks
5
more ...