European Commission Libraries Catalogue
http://ec.europa.eu/eclas/Fhttp://ec.europa.eu/eclas/F
Max Planck Institute for Comparative Public Law and International Law – Heidelberg
http://www.mpil.de/ww/en/pub/library.cfm
Max Planck Institute for Private Law – Hamburg
http://www.mpipriv.de/ww/en/pub/library.htm
Peace Palace Library
http://www.ppl.nl