Content Provider
Directory of Open Access Journals: DOAJ Articles
84
Biodiversity Heritage Library (BHL)
65
Bavarian Digital Repository (BDR - Bayerische Staatsbibliothek Munich, BSB)
3
University of Michigan: Digital Collections
3
DIAL@USL-B (Université Saint-Louis, Bruxelles)
2
Springer Nature (via Crossref)
2
Hathi Trust Digital Library
1
Informa (via Crossref)
1
Münster University (WWU): miami
1