On the Conflict of Justice blog (which I only came across today), there is a great article debunking a claim one finds in works such as Fawn Brodie's No Man Knows My History and the CES Letter, namely, that Thomas Dick influenced Joseph Smith's theology:
Did Joseph Smith Get The Book Of Abraham Cosmology From ‘Philosophy Of A Future State’?
One should also pursue Edward (Ted) Jones' M.A. thesis examining this issue, too:
Ted Jones, The Theology of Tomas Dick and Its Possible Relationship to that of Joseph Smith (M.A. Thesis, BYU Provo, 1969)
Did Joseph Smith Get The Book Of Abraham Cosmology From ‘Philosophy Of A Future State’?
One should also pursue Edward (Ted) Jones' M.A. thesis examining this issue, too:
Ted Jones, The Theology of Tomas Dick and Its Possible Relationship to that of Joseph Smith (M.A. Thesis, BYU Provo, 1969)