The WorldCat link appears within all four available Google Book views:
- the Full View offering access to the full content of a digitized title;
- the Limited Preview that lets you read only several pages of the book;
- the Snippet View that contextually presents passages of the book which contain your search terms; and
- the basic record view which does not feature a content preview.
Google Books Advanced Book Search also has a Library Catalogs option that allows you to limit a search to "Library Catalogs." The searches in a vast number of library catalogs is a result of a project starting in 2005 called the Online Computer Library Center or OCLC. Wikipedia.
OCLC and its member libraries cooperatively produce and maintain WorldCat—the OCLC Online Union Catalog, the largest Online Public Access Catalog (OPAC) in the world. WorldCat has holding records from public and private libraries worldwide. WorldCat is available through libraries and university computer networks. The Open WorldCat program makes records of library-owned materials in OCLC's WorldCat database available to Web users on popular Internet search, bibliographic and bookselling sites. In October 2005, the OCLC technical staff began a wiki project allowing readers to add commentary and structured-field information associated with any WorldCat record.OCLC describes itself as a "nonprofit, membership, computer library service and research organization dedicated to the public purposes of furthering access to the world’s information and reducing information costs. More than 72,000 libraries in 86 countries and territories around the world use OCLC services to locate, acquire, catalog, lend and preserve library materials."
Now, what does all this have to do with genealogy? Plenty. A search in WorldCat.org on the term genealogy brought up 474,804 items. If I find a reference to a book or other publication that I would like to use for research, the first place I go to search is WorldCat.org because I will then know if I can find the book through a library or through Interlibrary loan. If the book is located in a participating library, I can use my own library card at my local library to have a copy sent to my library for checkout. Essentially, almost the entire world of research is available to me at my own city's public library. I also not limited by the collections at a the nearby university libraries either.