Content Provider
University of Groningen research database
69
Wageningen UR (University & Research Centre): Digital Library
12
Biblioteca Virtual de Defensa (BVD - Ministerio de Defensa de España)
11
Ghent University Academic Bibliography
3
Biblioteca Virtual del Patrimonio Bibliográfico
2
Utrecht University Repository
2
University of Liège: ORBi (Open Repository and Bibliography)
1