OCLC

This is a worldwide library that provides services and research to improve access to the information available in the world. This catalogue has millions of records harvesting from an open access collection using the Open Archives Protocol for Metadata Harvesting (OAI-PMH). There are more than 25 million records and more than 1100 contributors. 

OCLC:
http://www.oclc.org/europe/en_us/home.html?redirect=true