Content Provider
DataCite Metadata Store (German National Library of Science and Technology)
5,917
David Rumsey Historical Map Collection (Cartography Associates)
1,481
University of Wisconsin, Milwaukee: UWM Libraries Digital Collections
1,415
IEDA: Marine-Geo Digital Library (via DataONE)
1,237
Memorial University of Newfoundland: Digital Archives Initiative (DAI)
848
USGS Science Data Catalog (via DataONE)
768
Directory of Open Access Journals: DOAJ Articles
704
Unknown
657
PANGAEA - Data Publisher for Earth & Environmental Science
647
Arctic Data Center (via DataONE)
618
Defense Technical Information Center: DTIC Technical Reports database
489
NOAA NCEI Environmental Data Archive (via DataONE)
441
Cambridge University Press
404
Research Data Australia (Australian National Data Service - ANDS)
322
Open Parks Network
276
WikiBooks - Open-content textbooks
183
MDPI Open Access Publishing
151
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe)
129
PubMed Central (PMC)
126
Zenodo
116
University of Washington, Seattle: Digital Collections
112
German Aerospace Center: elib - DLR electronic library
108
University of Calgary Journal Hosting
108
Hathi Trust Digital Library
101
CyberLeninka (Scientific Electronic Library)
96
RePEc (Research Papers in Economics)
88
Copernicus Publications: E-Journals
85
DataverseNO
82
Université de Nantes: HAL-UNIV-NANTES
74
Natural Environment Research Council: NERC Open Research Archive
72
University of Tromsø: Munin Open Research Archive
71
Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center)
67
Wiley Online Library
64
NASA Technical Reports Server (NTRS)
63
National Research Council Canada: NRC Publications Archive
62
Niedersächsisches Online-Archiv NOA
58
IOP Publishing (via Crossref)
54
Washington State University: WSU Libraries Digital Collections
54
North Dakota State University (NDSU): Digital Horizons
53
University of Southampton: e-Prints Soton
53
Memorial University of Newfoundland: Research Repository
52
Springer Nature (via Crossref)
51
Aalto University Publication Archive (Aaltodoc)
50
ArXiv.org (Cornell University Library)
48
Informa (via Crossref)
48
Technical University of Denmark: DTU Orbit
48
National Institute of Polar Research Repository, Japan
45
Université Laval: CorpusUL
45
NTNU Open Archive (Norwegian University of Science and Technology)
44
Frontiers: Figshare
43
more ...