Felix III - Short biography of Pope St. Felix III, by Karen Rae Keck. - http://www2.evansville.edu/ecoleweb/glossary/felixiii.html
St. Felix II - Account of his pontificate. - http://www.cfpeople.org/Books/Pope/POPEp48.htm
Pope St. Felix III - Felix II was an antipope, irregularly imposed by the Arians while Pope Liberius was still alive, so Pope St. Felix III is sometimes called Felix II. Pope St. Felix III was much involved in battling heresy, and died in 492. Article in the Catholic Encyclo - http://www.newadvent.org/cathen/06030b.htm