Content Provider
Open Parks Network
2,191
DataCite Metadata Store (German National Library of Science and Technology)
682
Unknown
496
Washington State University: WSU Libraries Digital Collections
412
Directory of Open Access Journals: DOAJ Articles
368
University of Calgary Journal Hosting
344
Canadian Science Publishing (via Crossref)
293
The Seattle Public Library Special Collections Online
275
University of Lethbridge Digitized Collections
204
Cambridge University Press
171
Hathi Trust Digital Library
156
University of British Columbia: cIRcle - UBC's Information Repository
151
University of Alaska: ScholarWorks@UA
136
Wiley Online Library (via Crossref)
133
PubMed Central (PMC)
119
PANGAEA - Data Publisher for Earth & Environmental Science
114
Wiley Online Library
101
Theses Canada/Thèses Canada (Library and Archives Canada)
92
ScienceDirect (Elsevier - via Crossref)
89
The Library of Congress: American Memory
79
Defense Technical Information Center: DTIC Technical Reports database
75
Biodiversity Heritage Library (BHL)
74
Copernicus Publications: E-Journals
68
Springer Nature (via Crossref)
67
Canadian Science Publishing
57
Niedersächsisches Online-Archiv NOA
54
Cambridge University Press (via Crossref)
52
University of the Pacific, McGeorge School of Law: Scholarly Commons
52
University of the Pacific: Scholarly Commons
52
Informa (via Crossref)
47
MDPI Open Access Publishing
44
PRISM - University of Calgary Digital Repository
44
Carleton University's Institutional Repository
43
University of Michigan: Digital Collections
43
uO Research (University of Ottawa - uOttawa)
38
VIURRSpace (Royal Roads University and Vancouver Island University)
35
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe)
34
Oklahoma State University: Digital Collections @ OKSTATE Library
32
The Canadian Field-Naturalist (E-Journal)
31
University of Alberta: Era - Education and Research Archive
31
Borealis
30
University of Tromsø: Septentrio Academic Publishing
29
Summit - SFU Research Repository (Simon Fraser University)
26
University of Toronto: Research Repository T-Space
26
WikiBooks - Open-content textbooks
26
University of North Texas: UNT Digital Library
25
University of Saskatchewan: eCommons@USASK
25
Érudit.org (Université Montréal)
25
HighWire Press (Stanford University)
23
SAGE Publications (via Crossref)
23
more ...