Content Provider
HighWire Press (Stanford University)
21
Unknown
15
PubMed Central (PMC)
11
Copernicus Publications: E-Journals
4
MDPI Open Access Publishing
4
Queensland University of Technology: QUT Digital Collections
3
W&M ScholarWorks
3
DataCite Metadata Store (German National Library of Science and Technology)
1
Defense Technical Information Center: DTIC Technical Reports database
1
DigiZeitschriften: The German digital journal archive (Göttingen University Library)
1
Norwegian Institute for Nature Research: Brage NINA
1
University of Massachusetts: ScholarWorks@UMass Amherst
1