The CLIO Catalog is the best way to search for books on Jewish Studies both at Barnard and Columbia. To search for books not held by Barnard or Columbia, WorldCat searches libraries worldwide. If a title isn't available via Columbia University Libraries, you may request it via Borrow Direct or Interlibrary Loan.
Most books relating to Jewish Studies will fall into these call number classes from the Library of Congress system, which most of the Barnard & Columbia libraries use.