Content Provider
LeibnizOpen (The Leibniz Association)
21
PANGAEA - Data Publisher for Earth & Environmental Science
5
DataCite Metadata Store (German National Library of Science and Technology)
3
Unknown
2
Defense Technical Information Center: DTIC Technical Reports database
1
HighWire Press (Stanford University)
1
Max Planck Society: MPG.PuRe
1
Polar Research (E-Journal)
1
Renate - Repositorium für Naturwissenschaften und Technik (TIB Hannover)
1
University of Wisconsin, Milwaukee: UWM Libraries Digital Collections
1
Wiley Online Library
1