1. Primary sources

Europeana

European history
primary sources

• Portal
• Recension of small digital humanities projects publishing primary sources
• Very good way to discover ressources
• They are assessed by the EHPS team
• Edited by the department of history at the European University Institute
  

National libraries

Check out websites of national libraries.

See for instance Gallica.

Important notably to get access to digitised journals, see BNL's digital collections.

Subject oriented
suggestions

European integration / XXth century european
history

1. European integration
   • CVCE.eu
   • Archive of European integration
2. Technology
   • Europe interrupted
     

2. Secondary sources

Google Books
Google Scholar

• Google books
• Many books on-line (who knows really how?)
  
• Interesting tools: Google ngrams

• Google Scholar
• But, still, interesting tools: cf. Harzing's PoP - who cites who.
  

In French

• Persee.fr
• cairn.info
• revues.org
• Lots of libraries
  

In German

• Perspectivia.net
• recensio.net
  

In English

JSTOR

Sage

Many more...