Internet Encyclopedia of Philosophy: Diogenes Laertius: Concise article on this ancient biographer.
Lives of the Philosophers: Online text of C.D. Yonge's translation.
Notes on Diogenes Laertius: A criticism of this author's reliability, based on his Life of Socrates.
The Manuscripts of "The Lives and Opinions of Eminent Philosphers": Hicks' notes from his 1925 translation of this text.
Wikipedia: Diogenes Laertius: Article drawing on the 1911 Britannica.