Content Provider
Hathi Trust Digital Library
17
University of Michigan: Digital Collections
11
Yale University: EliScholar
10
Bavarian Digital Repository (BDR - Bayerische Staatsbibliothek Munich, BSB)
8
OLAC: Open Language Archives Community
8
DataCite Metadata Store (German National Library of Science and Technology)
4
Harvard University: Harvard Collections
4
Princeton Theological Seminary: Theological Commons
4
DataCite
1
Digital Collections of Colorado (Colorado State University)
1
Mountain Scholar (Digital Collections of Colorado and Wyoming)
1
Project Gutenberg (PG)
1
The Library of Congress: American Memory
1