On the relation between Nori Motives and Kontsevich Periods
  We show that the spectrum of Kontsevich's algebra of formal periods is a torsor under the motivic Galois group for mixed motives over the rational numbers. This assertion is stated without proof by Kontsevich and originally due to Nori. In a series of appendices, we also provide the necessary details on Nori's category of motives. 
Annette Huber, Stefan M\"uller-Stach
math.AG math.KT math.NT