A Guide to Thirteenth Century Theologians: Roger Bacon: Dates, extant works, recent bibliography.
Catholic Encyclopedia: Roger Bacon: 1912 article by Theophilus Witzel, providing an extensive overview of Bacon's life and works.
MacTutor History of Mathematics: Roger Bacon: Concise biographical article, with links to articles on related thinkers.
Memoirs of Popular Delusions: Roger Bacon: Excerpt from this work by Charles Mackay.
Roger Bacon's Place in the History of Alchemy: Footnoted journal article by Edmund Brehm, discussing Bacon's contributions to alchemy. Features a diagram showing how alchemy fit into Bacon's world system.