Content Provider
DataCite Metadata Store (German National Library of Science and Technology)
1,339
Zenodo
179
Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center)
120
Unknown
72
PANGAEA - Data Publisher for Earth & Environmental Science
65
Biodiversity Heritage Library (BHL)
57
Cambridge University Press
50
Hathi Trust Digital Library
48
the clark - Digital Collections (Sterling and Francine Clark Art Institute Library)
46
Springer Nature (via Crossref)
38
DigiZeitschriften: The German digital journal archive (Göttingen University Library)
36
University of Michigan: Digital Collections
36
Bavarian Digital Repository (BDR - Bayerische Staatsbibliothek Munich, BSB)
31
JSTOR (via Crossref)
31
David Rumsey Historical Map Collection (Cartography Associates)
30
e-periodica (Swiss journals online, ETH Zurich)
27
University of Alberta: Era - Education and Research Archive
25
Directory of Open Access Journals: DOAJ Articles
24
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel)
24
University of Washington, Seattle: Digital Collections
24
Informa (via Crossref)
22
Washington State University: WSU Libraries Digital Collections
22
LeibnizOpen (The Leibniz Association)
21
University of Wisconsin, Milwaukee: UWM Libraries Digital Collections
20
Frankfurt/Main University Library: Digitale Sammlungen
19
Defense Technical Information Center: DTIC Technical Reports database
18
The Library of Congress: American Memory
17
Norsk Polarinstitutt: Brage NP
16
Norwegian Polar Institute: Brage NP
16
The Royal Society (via Crossref)
15
Wiley Online Library (via Crossref)
15
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe)
14
IODE-UNESCO: OceanDocs - E-Repository of Ocean Publications
13
International Association of Aquatic and Marine Science Libraries and Information Centers (IAMSLIC): Aquatic Commons
13
North Dakota State University (NDSU): Digital Horizons
13
WikiBooks - Open-content textbooks
13
Copernicus Publications: E-Journals
12
Wiley Online Library
11
Gallica - bibliothèque numérique de la Bibliothèque nationale de France (BnF)
10
Niedersächsisches Online-Archiv NOA
10
Open Parks Network
9
Institut national des sciences de l'Univers: HAL-INSU
8
ScienceDirect (Elsevier)
8
Université de Nantes: HAL-UNIV-NANTES
8
Brill (via Crossref)
7
Doria (National Library of Finland)
7
University of Chicago Press (via Crossref)
7
De Gruyter (via Crossref)
6
Dryad Digital Repository (Duke University)
6
NASA Technical Reports Server (NTRS)
6
more ...