OK, now if I had to list the top five websites I use the most frequently, WorldCat.org would always be on the list. There is nothing else close. Over 74,000 libraries in 170 countries have used OCLC services to locate, acquire, catalog, lend, preserve and manage library materials.
If you haven't used WorldCat.org, you haven't done your homework for any type of research. Click on the link and start looking in WorldCat.org.