The Wayback Machine - https://web.archive.org/web/20210727111802/https://www.mpi.lu/library/collection/useful-links/

Library catalogues

a-z.lu - collective search engine of 87 Luxembourgish libraries

BnL - Legal & other resources

Find-eR - searches the European Commission libraries collections 

HEIDI - Catalogue for libraries of Heidelberg University

KVK - Karlsruhe Virtual Catalog

Library of Congress

Library of the Court of Justice of the EU / Curius - new catalogue

Open Library

Peace Palace Library

Staatsbibliothek zu Berlin

SWB Online-Katalog - 1200 libraries in Baden-Wuerttemberg, Saxony, Saarland, and Rhineland- Palatinate

theses.fr - Database providing access for more than 66,000 awarded or in-progress theses.

UNBISnet - UN Bibliographic Information System

WorldCat - 10,000 libraries worldwide          

Quick links