WorldCat This link opens in a new windowWorldCat is the world’s largest network of library content. Thousands of libraries have entered their information about millions of books, magazines, movies, songs, maps, genealogical records, research theses and so much more . This database is extremely useful in locating material outside JCKL’s holdings and using InterlIbrary Loan to access almost half-a-billion records from nearly 18,000 libraries around the world.