Collection
Directory of Open Access Books
51
World Bank E-Library Archive
18
Eighteenth Century Collections Online / ECCO
9
Digi20
4
Cambridge Books Online
3
Mohr Siebeck eBooks
2
OAPEN
2
DeGruyter MPG Collection
1
Duncker & Humblot eBooks 2007-
1
Elsevier eBook collection Mathematics
1
Oxford University Press
1