Michael F. Bird links to “Did Jesus Exist? Searching for Evidence Beyond the Bible” – an article at Bible History Daily by Lawrence Mykytiuk.
Bird calls it “a depressing read if you’re a Jesus Mythicist.”
He also recommends Robert E. Van Voorst, Jesus Outside the New Testament: An Introduction to the Ancient Evidence (Grand Rapids, MI: Eerdmans, 2000).
For more information on this subject, go to Wintery Knight’s post on the same link. As usual, he provides valuable commentary, organization of ideas, and additional resources (e.g. link to Gary Habermas online chapter about extrabiblical evidence for Jesus).