WorldCat

WorldCat is the world's largest network of library content and services. WorldCat libraries are dedicated to providing online access to their resources. Use this global catalog of library collections to search for books, DVDs, CDs and articles from the collections of 10,000 libraries worldwide. Currently over 2+ billion items are listed. 
Tip: Do a phrase search for your family name + family - "Smith family" to locate published family histories.