Jonathan - Biblical biography of the steadfast friend of King David. - http://www.execulink.com/~wblank/20000521.htm
Catholic Encyclopedia: Jonathan - Identifies four persons in particular of this name in the Old Testament. - http://www.newadvent.org/cathen/08499b.htm
Jewish Encyclopedia: Jonathan - Overview of the son of Saul from the traditional Jewish perspective, including Talmudic commentary. - http://www.jewishencyclopedia.com/view.jsp?artid=398&letter=J