3 links
Catholic Encyclopedia: Don Isaac Abrabanel
newadvent.org
Short review of his life and writings, by Romain Butin.
Great Leaders of Our People: Don Yitzchak Abrabanel
ou.org
Biographical article with an emphasis on the Judaic aspects of this thinker's career.
Isaac ben Judah Abravanel: Statesman, Financier, and Biblical Commentator
jewishgates.com
Biographical article from JewishGates.com.