Alexander Goncharov: Volumes of hyperbolic manifolds and mixed Tate motives. J. Amer. Math. Soc. 12 (1999), no. 2, 569–618. pdf
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Michael Gromov: Hyperbolic manifolds (according to Thurston and Jørgensen). Bourbaki Seminar, Vol. 1979/80, pp. 40–53, Lecture Notes in Math., 842, Springer, Berlin-New York, 1981. pdf