Expository accounts of the Thurston norm

Other than Thurston's original paper (which I find quite hard to read), are there any expositions of the basic properties of the Thurston norm? In particular, I'm interested in a proof of his characterization of which homology classes can be represented by fibers. Some parts of this can be found in Kapovich's book, but he does not discuss the result I alluded to in my previous sentence.

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You could have a look at Chapter 10 of Candel Conlon, Foliations II. books.google.com/… –  Ian Agol Jan 12 '12 at 5:26
Give a look also to Calegari - Foliations and the geometry of 3-manifolds. –  Francesco Lin Jan 12 '12 at 11:10
Actually, I think Thurston's paper IS the canonical reference, because most people find it quite well-written. –  Igor Rivin Jan 12 '12 at 11:19