Motives for modular forms, Inventiones math. 100 (1990), 419-430

There are a number of confusing misprints in this paper. Also Proposition 2.0.2 is not stated correctly, although this does not affect what follows.

The same proof (with a lot more details, and hopefully fewer misprints) can now be found in the draft version of Chapter 7 of my book in preparation on higher regulators and modular forms.