Content Provider
OLAC: Open Language Archives Community
34
APS Digital Library (American Philosophical Society)
8
University of Michigan: Digital Collections
7
Hathi Trust Digital Library
5
The Online Books Page (Penn Libraries, University of Pennsylvania)
3
Biodiversity Heritage Library (BHL)
2
American Museum of Natural History: AMNH scientific publications
1
DataCite Metadata Store (German National Library of Science and Technology)
1
Princeton Theological Seminary: Theological Commons
1