Book Suggestions on the Historicity of the Ascension?

Over the last year I've spent a lot of time and energy reading books and articles on the "historicity" of the resurrection of Jesus, and it's been a largely positive experience—I am slightly less certain than I was before that the resurrection never actually occurred as a historical event.

However, something that has continued to be problematic for me, particularly when it comes to historical studies, is how the resurrection and ascension are often sort of lumped together both historically and literarily. The ascension of Jesus is only mentioned explicitly in Luke/Acts, and implicitly in John (20:17), so it appears that the ascension is part of a much later Jesus tradition. It also relies upon an ancient understanding of the cosmos (i.e. Where did Jesus physically go, anyway? Mars?). My personal belief is that while I can accept the historicity of the resurrection, the ascension is most likely a theological embellishment intended to paint Jesus as greater than Elijah, or—even more probably—to figure out what to do with the character of the resurrected Jesus after he was raised from the dead.

So I'm curious as to whether anyone knows of any good books that argue both sides of the debate on the historicity of the ascension? Do you have any particular thoughts on the ability to accept either the resurrection or the ascension, or both, as historical events? Furthermore, if one argues for the historicity of the ascension of Jesus, are they not then obligated to consider the historicity of the ascension of Elijah in his fiery chariot, or even the historicity of the ascension of the Prophet Muhammad?

Jesus Mythicists? I Don't Believe They Exist.

R. Joseph Hoffmann over at The New Oxonian has recently been posting a series of biting critiques of the recent (though semi-annual) surge in Jesus Mythicism. His latest post is called "The Passion of the Christ-Deniers," and can be found here. Hoffmann suggests that the urge for mythicists to "prove" the non-existence of a historical Jesus comes from an overreaction against conservative fundamentalist theology and high ecclesial bureaucracy, and points the finger at folks on both sides of the aisle (so to speak).

I agree with most of Hoffmann's sentiments. The question of a historical figure's existence is not an inherently theological issue, nor should it be. I have seen few non-Muslims and non-Buddhists question the historicity of Mohammed or Siddharta Gautama. However, I do find it perfectly reasonable to allow one's theological perspective to be informed by historical questions, and using them to help to frame his or her perception of the past.