Content Provider
PubMed Central (PMC)
338
HighWire Press (Stanford University)
39
LeibnizOpen (The Leibniz Association)
19
Unknown
3
Apollo - University of Cambridge Repository
2
DigiZeitschriften: The German digital journal archive (Göttingen University Library)
2
Carolina Digital Repository (UNC - University of North Carolina)
1
DataCite Metadata Store (German National Library of Science and Technology)
1
Lund University Publications (LUP)
1
Repositório Aberto da Universidade do Porto
1
Universidade do Algarve: Sapienta
1