WorldCat, available on the FirstSearch interface, is a combined catalog for over 70,000 libraries in 170 countries. The information is updated daily.
Digitized books
Google Books and Google Buchsuche Deutschland Brings together millions of titles from the dawn of printing to the present day. Out-of-copyright books are available in full text.
Internet Archive Over 2,000,000 digitized books and manuscripts.
Hathi Trust A shared digital repository of United States' great research libraries.