3 links
Catholic Encyclopedia: John of Salisbury
newadvent.org
Article on his life and thought by P. Coffey.
Columbia Encyclopedia: John of Salisbury
bartleby.com
Concise entry on this medieval scholar, from the 2001 edition.
English Scholars of Paris: John of Salisbury
bartleby.com
Section from the Cambridge History of English and American Literature, covering his life and work in some detail.