♦ Academic Search Complete: Articles from journals in many fields.
♦ Philosopher's Index: Some titles in Philosopher's Index are full-text articles, other titles may direct to the Full-Text Finder that leads to other databases; still, other titles can be provided at Borrow from Other Libraries. Simply follow where the links take you. (use Central Index)
Logic & Proofs (part of Open Learning Initiative) -- the first few chapters are freely available and provide an overview of the topic. Additional in-depth chapters require a paid account. NOTE: This tool requires Flash software, so portions will not run on a Mac.